ISTAT - Istituto Nazionale di Statistica
MSD for the Census population (ESMS_CENSUS_MSD 1.1 ESTAT)
Census 2011 round
2011 - A0
1. Contact
1.1 Contact organisation

Istituto nazionale di statistica (ISTAT)

1.2 Contact organisation unit

Dipartimento per i censimenti e gli archivi amministrativi e statistici (DICA)

1.3 Contact name
1.4 Contact person function
1.5 Contact mail address

via Oceano Pacifico 171, 00142 Roma, Italia

1.6 Contact email address
1.7 Contact phone number
1.8 Contact fax number
2. Metadata update
2.1 Metadata last certified
01/04/2014
2.2 Metadata last posted
01/04/2014
2.3 Metadata last update
01/04/2014
3. Statistical presentation
3.1 Data description

Not available.

3.2 Classification system

ISCO-08, NACE Rev. 2, etc.

3.3 Coverage - sector
3.4 Statistical concepts and definitions
3.4.1 Statistical concepts and definitions - Usual residence

Usual residence means the place where a person normally spends the daily period of rest, regardless of temporary absences for purposes of recreation, holidays, visits to friends and relatives, business, medical treatment or religious pilgrimage.
Persons usually resident in the place of enumeration but absent, or expected to be absent, at the time of the census for less than one year shall be considered as temporarily absent persons and thus included in the total unsually population. In contrast, persons living or expected to live outside the place of enumeration for one year or more shall not be considered temporarily absent and shall therefore be excluded from the total population. This is regardless of the length of visits that they may pay to their families from time to time.
Persons who are enumerated but do not meet the criteria for usual residence in the place of enumeration, i.e. do not live or do not expect to live in the place of enumeration for a continuous period of at least 12 months, are considered temporarily present and are therefore not counted in the total usually resident population.

3.4.2 Statistical concepts and definitions - Sex

Male/Female   

3.4.3 Statistical concepts and definitions - Age

The age reached at the reference date (in completed years).

3.4.4 Statistical concepts and definitions - Marital status

Marital status is the (legal) conjugal status of an individual in relation to the marriage laws of the country (de jure status).
A person shall be classified according to his/her most recently acquired legal marital status at the reference date.
'Registered partnerships' are reported only by countries that have a legal framework regulating partnerships that:
(a) lead to legal conjugal obligations between two persons;
(b) are not marriages;
(c) prevent persons to commit themselves into multiple partnerships with different partners.
In countries where the legislation includes provisions for married partners to be 'legally separated', such 'legally separated' persons are classified under 'married'.

In Italy the legal basis is included in the Italian Constitution (paragraph 29) and in the civil code (Libro I Titolo VI, par. 82 et seq.)

The legal basis establishes:

- Opposite sex marriage

- The minimum age for marriages (16 years)

- The possibility to divorce or legally separate

Same-sex marriages and opposite-sex and same sex-registered partnerships are not allowed.

3.4.5 Statistical concepts and definitions - Family status

The family nucleus is defined in the narrow sense, that is as two or more persons who belong to the same household and who are related as husband and wife, as partners in a registered partnership, as partners in a consensual union, or as parent and child. Thus a family comprises a couple without children, or a couple with one or more children, or a lone parent with one or more children. This family concept limits relationships between children and adults to direct (first-degree) relationships, that is between parents and children.
Child (son/daughter) refers to a blood, step- or adopted son or daughter (regardless of age or marital status) who has usual residence in the household of at least one of the parents, and who has no partner or own children in the same household. Foster children are not included. A son or daughter who lives with a spouse, with a registered partner, with a partner in a consensual union, or with one or more own children, is not considered to be a child. A child who alternates between two households (for instance if his or her parents are divorced) shall consider the one where he or she spends the majority of the time as his or her household. Where an equal amount of time is spent with both parents the household shall be the one where the child is found at the time on census night.
The term couple shall include married couples, couples in registered partnerships, and couples who live in a consensual union.
Registered partnerships are reported only by countries that have a legal framework regulating partnerships that:
(a) lead to legal conjugal obligations between two persons;
(b) are not marriages;
(c) prevent persons to commit themselves into multiple partnerships with different partners.
Two persons are considered to be partners in a 'consensual union' when they
— belong to the same household, and
— have a marriage-like relationship with each other, and
— are not married to or in a registered partnership with each other.
'Skip-generation households' (households consisting of a grandparent or grandparents and one or more grandchildren, but no parent of those grandchildren) are not included in the definition of a family.

3.4.6 Statistical concepts and definitions - Household status

Private households may be defined according to the 'housekeeping concept' , or, if this is not possible, Member States may apply the 'household-dwelling' concept.
1. Housekeeping concept
According to the housekeeping concept, a private household is either:
(a) A one-person household, that is a person who lives alone in a separate housing unit or who occupies, as a lodger, a separate room (or rooms) of a housing unit but does not join with any of the other occupants of the housing unit to form part of a multiperson household as defined below; or
(b) A multiperson household, that is a group of two or more persons who combine to occupy the whole or part of a housing unit and to provide themselves with food and possibly other essentials for living. Members of the group may pool their incomes to a greater or lesser extent.
2. Household-dwelling concept
The household-dwelling concept considers all persons living in a housing unit to be members of the same household, such that there is one household per occupied housing unit. In the household dwelling concept, then, the number of occupied housing units and the number of households occupying them is equal, and the locations of the housing units and house­ holds are identical.
The category 'Persons living in a private household' comprises 'Persons in a family nucleus' and 'Persons not in a family nucleus'. The category 'Persons in a family nucleus' comprises all persons who belong to a private household that contains a family nucleus of which they are a member. 'Persons not in a family nucleus' comprises all persons who either belong to a non-family household or to a family household without being member of any family nucleus in that household.
A non-family household can be a one-person household ('Living alone') or a multiperson household without any family nucleus. The category 'Not living alone' comprises persons that live either in a multiperson household without any family nucleus or in a family household without being member of any family nucleus in that household. Persons who belong to a skip-generation household and who are not member of any family nucleus in that household shall be classified in the optional category 'Persons living in a household with relative(s)'.
The term 'son/daughter' is defined as the term 'child' in the technical specifications for the topic 'Family status'. 'Husband/wife couple' means a married opposite-sex couple.
'Registered partnership' is defined as in the technical specifications for the topic 'Legal marital status'. 'Consensual union' is defined as in the technical specifications for the topic 'Family status'.
The category 'Partners' comprises 'Persons in a married couple', 'Partners in a registered partnership' and 'Partners in a consensual union'.
'Primary homeless persons' are persons living in the streets without a shelter that would fall within the scope of living quarters as defined in the technical specifications for the topic 'Type of living quarters'.

Italy applied the ‘housekeeping’ concept to identify private households. The relationships between household members are identified by relation to reference person.

3.4.7 Statistical concepts and definitions - Current activity status

Current activity status' is the current relationship of a person to economic activity, based on a reference period of one week, which may be either a specified, recent, fixed, calendar week, or the last complete calendar week, or the last seven days prior to enumeration.
The 'currently economically active population' comprises all persons who fulfil the requirements for inclusion among the employed or the unemployed.
'Employed' persons comprise all persons aged 15 years or over who during the reference week:
(a) performed at least one hour of work for pay or profit, in cash or in kind, or
(b) were temporarily absent from a job in which they had already worked and to which they maintained a formal attachment, or from a self-employment activity.
The 'unemployed' comprise all persons aged 15 years or over who were:
(a) 'without work', that is, were not in wage employment or self-employment during the reference week; and
(b) 'currently available for work', that is, were available for wage employment or self-employment during the reference week and for two weeks after that; and
(c) 'seeking work', that is, had taken specific steps to seek wage employment or self-employment within four weeks ending with the reference week.
The category 'Currently not economically active' includes persons below the national minimum age for economic activity.
In ascribing a single activity status to each person, priority is given to the status of 'employed' in preference to 'unemployed', and to the status of 'unemployed' in preference to 'not economically active'.

3.4.8 Statistical concepts and definitions - Occupation

Occupation' refers to the type of work done in a job (that is the main tasks and duties of the work). Persons doing more than one job are allocated an occupation based on their main job, which is identified according to the time spent on the job or, if not available, to the income received.
The breakdown by occupation is available for persons aged 15 or over that were:
— employed during the reference week, or
— unemployed during the reference week, but have ever been in employment
Persons are classified according to the occupation they had during their most recent employment. The categories included in the breakdown 'occupation' correspond to the major groups of the ISCO-08 (COM) classification.
Persons under the age of 15 years, as well as persons aged 15 or over that were:
— not economically active during the reference week, or
— unemployed, never worked before (i.e. they have never been employed in their lives)
are classified under 'not applicable'.
The allocation of a person within the breakdowns of the topics 'Occupation', 'Industry' and 'Status in employment' is based on the same job.

3.4.9 Statistical concepts and definitions - Industry

Industry (branch of economic activity) is the kind of production or activity of the establishment (or similar unit) in which the job of a currently economically active person is located.
Persons doing more than one job shall be allocated an industry (branch of economic activity) based on their main job, which is to be identified according to the time spent on the job or (if not available) the income received.
The breakdown by industry is available for persons aged 15 or over that were:
— employed during the reference week, or
— unemployed during the reference week, but have ever been in employment
Persons are classified according to the industry they worked in during their most recent employment. The categories included in the breakdown 'industry' list the 21 sections of the NACE Rev. 2 classification and appropriate aggregates.
Persons under the age of 15 years, as well as persons aged 15 or over that were:
— not economically active during the reference week, or
— unemployed, and have never worked before (i.e. have never been employed in their lives)
are classified under 'not applicable'.
The allocation of a person within the breakdowns of the topics 'Occupation', 'Industry' and 'Status in employment' is based on the same job.

3.4.10 Statistical concepts and definitions - Status in employment

In order to ensure consistency with the 2001 census data, 'external workers' were counted under 'employees'. In the case of specific European directives, external workers can be aggregated with other categories.

An 'employee' is a person who works in a 'paid employment' job, that is a job where the explicit or implicit contract of employment gives the incumbent a basic remuneration, which is independent of the revenue of the unit for which he/she works.
An 'employer' is a person who, working on his or her own account or with a small number of partners, holds a 'self-employment' job and, in this capacity, on a continuous basis (including the reference week) has engaged one or more persons to work for him/her as 'employees'.
If a person is both employer and employee, he/she shall be allocated to only one group according to the time spent on the job or (if not available) the income received.
An 'own-account worker' is a person who, working on his/her own account or with one or a few partners, holds a 'self-employment job' and has not engaged, on a continuous basis (including the reference week), any 'employees'.
A 'contributing family worker' is a person who
— holds a 'self-employment’ job in a market-oriented establishment operated by a related person, living in the same household, and
— cannot be regarded as a partner (that is an employer or own-account worker) because the degree of commitment to the operation of the establishment, in terms of working time or other factors to be determined by national circumstances, is not at a level comparable to that of the head of the establishment.
A 'member of a producers' cooperative' is a person who holds a 'self-employment' job in an establishment organised as a coop­ erative, in which each member takes part on an equal footing with other members in determining the organisation of production, sales and/or other work, the investments and the distribution of the proceeds among the members.

3.4.11 Statistical concepts and definitions - Place of work

The location of the place of work is the geographical area in which a currently employed person does his/her job.
The place of work of those mostly working at home is the same as their usual residence. The term 'working' refers to work done as an 'employed person' as defined under the topic 'Current activity status'. 'Mostly' working at home means that the person spends all or most of the time working at home, and less, or no, time in a place of work other than at home.

3.4.12 Statistical concepts and definitions - Educational attainment

'Educational attainment' refers to the highest level successfully completed in the educational system of the country where the education was received. All education which is relevant to the completion of a level is taken into account even if this was provided outside schools and universities.
Persons aged 15 years or over are classified under only one of the categories according to their educational attainment (highest completed level). Persons under the age of 15 years are classified under 'not applicable'.

3.4.13 Statistical concepts and definitions - Size of the locality

A locality is defined as a distinct population cluster, that is an area defined by population living in neighbouring or contiguous buildings. Such buildings may either:
(a) form a continuous built-up area with a clearly recognisable street formation; or
(b) though not part of such a built-up area, comprise a group of buildings to which a locally recognised place name is uniquely attached; or
(c) though not meeting either of the above two criteria, constitute a group of buildings, none of which is separated from its nearest neighbour by more than 200 metres.

3.4.14 Statistical concepts and definitions - Place of birth

Place of birth is defined as the place of usual residence of the mother at the time of the birth, or, if not available, as the place in which the birth took place.
Information on the country of birth is based on the international boundaries existing on 1 January 2011. 'EU Member State', in particular, means a country that is a member of the European Union on 1 January 2011. The list of countries in the breakdown 'country/place of birth' serves only for statistical purposes.
For reporting countries that are EU Member States, the sub-category under the category 'other EU Member State' that refers to their Member State does not apply. For reporting countries that are not EU Member States, the category 'Other EU Member State' shall be read as 'EU Member State'.
The category 'Information not classifiable according to current borders' covers those persons whose country of birth existed at the time of the birth, but no longer exists at the time of the census, and who cannot be allocated uniquely to one country existing at the time of the census, i.e. according to current borders.
The category 'outside any country' covers persons for whom the usual residence of the mother at the time of the birth is not known and who where born outside the borders of any country, for example at sea or in the air.

3.4.15 Statistical concepts and definitions - Country of citizenship

Citizenship is defined as the particular legal bond between an individual and his/her State, acquired by birth or naturalisation, whether by declaration, option, marriage or other means according to the national legislation.
A person with two or more citizenships is allocated to only one country of citizenship, to be determined in the following order of precedence:
1. reporting country; or
2. if the person does not have the citizenship of the reporting country: other EU Member State; 3. if the person does not have the citizenship of another EU Member State: other country outside the European Union.
'EU Member State' means a country that is a member of the European Union on 1 January 2011. The list of countries in the breakdown 'Country of citizenship' shall only apply for statistical purposes.
For reporting countries that are EU Member States, the sub-category of the category 'citizenship not of reporting country, but other EU Member State' that refers to their Member State does not apply. For reporting countries that are not EU Member States, the category 'citizenship not of reporting country, but other EU Member State' shall be changed to 'citizenship of an EU Member State'.
Persons who are neither citizens of any country nor stateless and who have some but not all of the rights and duties associated with citizenship shall be classified under 'recognised non-citizens'.

3.4.16 Statistical concepts and definitions - Year of arrival in the country

The year of arrival is the calendar year in which a person most recently established usual residence in the country. The data for 2011 refer to the time span between 1 January 2011 and the reference date.

3.4.17 Statistical concepts and definitions - Residence one year before

This indicates the relationship between the current place of usual residence and the place of usual residence one year prior to the census. Children under one year of age are classified under 'Not applicable'.
For all persons that have changed their usual residence more than once within the year prior to the reference date, the previous place of usual residence is the last usual residence from which they moved to their current place of usual residence.

3.4.18 Statistical concepts and definitions - Housing arrangements

The topic 'Housing arrangements' covers the whole population and refers to the type of housing in which a person usually resides at the time of the census. This covers all persons who are usual residents in different types of living quarters, or who do not have a usual residence and stay temporarily in some type of living quarters, or who are roofless, sleeping rough or in emergency shelters, when the census is taken.
Occupants are persons with their usual residence in the places listed in the respective category.
'Conventional dwellings' are structurally separate and independent premises at fixed locations which are designed for permanent human habitation and are, at the reference date, either used as a residence, or vacant, or reserved for seasonal or secondary use.
'Separate' means surrounded by walls and covered by a roof or ceiling so that one or more persons can isolate themselves. 'Independent' means having direct access from a street or a staircase, passage, gallery or grounds.
'Other housing units' are huts, cabins, shacks, shanties, caravans, houseboats, barns, mills, caves or any other shelter used for human habitation at the time of the census, irrespective if it was designed for human habitation.
'Collective living quarters' are premises which are designed for habitation by large groups of individuals or several households and which are used as the usual residence of at least one person at the time of the census.
'Occupied conventional dwellings', 'other housing units' and 'collective living quarters' together represent'‘living quarters'. Any 'living quarter' must be the usual residence of at least one person.
The sum of occupied conventional dwellings and other housing units represents 'housing units'.
The homeless (persons who are not usual residents in any living quarter category) can be persons living in the streets without a shelter that would fall within the scope of living quarters (primary homelessness) or persons moving frequently between temporary accommodation (secondary homelessness).

3.4.19 Statistical concepts and definitions - Type of family nucleus

The family nucleus is defined in the narrow sense, that is as two or more persons who belong to the same household and who are related as husband and wife, as partners in a registered partnership, as partners in a consensual union, or as parent and child. Thus a family comprises a couple without children, or a couple with one or more children, or a lone parent with one or more children. This family concept limits relationships between children and adults to direct (first-degree) relationships, that is between parents and children.
Child (son/daughter) refers to a blood, step- or adopted son or daughter (regardless of age or marital status) who has usual residence in the household of at least one of the parents, and who has no partner or own children in the same household. Foster children are not included. A son or daughter who lives with a spouse, with a registered partner, with a partner in a consensual union, or with one or more own children, is not considered to be a child. A child who alternates between two households (for instance if his or her parents are divorced) shall consider the one where he or she spends the majority of the time as his or her household. Where an equal amount of time is spent with both parents the household shall be the one where the child is found at the time on census night.
The term couple shall include married couples, couples in registered partnerships, and couples who live in a consensual union.
Registered partnerships are reported only by countries that have a legal framework regulating partnerships that:
(a) lead to legal conjugal obligations between two persons;
(b) are not marriages;
(c) prevent persons to commit themselves into multiple partnerships with different partners.
Two persons are considered to be partners in a 'consensual union' when they
— belong to the same household, and
— have a marriage-like relationship with each other, and
— are not married to or in a registered partnership with each other.
'Skip-generation households' (households consisting of a grandparent or grandparents and one or more grandchildren, but no parent of those grandchildren) are not included in the definition of a family.

3.4.20 Statistical concepts and definitions - Size of family nucleus

The family nucleus is defined in the narrow sense, that is as two or more persons who belong to the same household and who are related as husband and wife, as partners in a registered partnership, as partners in a consensual union, or as parent and child. Thus a family comprises a couple without children, or a couple with one or more children, or a lone parent with one or more children. This family concept limits relationships between children and adults to direct (first-degree) relationships, that is between parents and children.
Child (son/daughter) refers to a blood, step- or adopted son or daughter (regardless of age or marital status) who has usual residence in the household of at least one of the parents, and who has no partner or own children in the same household. Foster children are not included. A son or daughter who lives with a spouse, with a registered partner, with a partner in a consensual union, or with one or more own children, is not considered to be a child. A child who alternates between two households (for instance if his or her parents are divorced) shall consider the one where he or she spends the majority of the time as his or her household. Where an equal amount of time is spent with both parents the household shall be the one where the child is found at the time on census night.
The term couple shall include married couples, couples in registered partnerships, and couples who live in a consensual union.
Registered partnerships are reported only by countries that have a legal framework regulating partnerships that:
(a) lead to legal conjugal obligations between two persons;
(b) are not marriages;
(c) prevent persons to commit themselves into multiple partnerships with different partners.
Two persons are considered to be partners in a 'consensual union' when they
— belong to the same household, and
— have a marriage-like relationship with each other, and
— are not married to or in a registered partnership with each other.
'Skip-generation households' (households consisting of a grandparent or grandparents and one or more grandchildren, but no parent of those grandchildren) are not included in the definition of a family.

3.4.21 Statistical concepts and definitions - Type of private household

Private households may be defined according to the 'housekeeping concept' , or, if this is not possible, Member States may apply the 'household-dwelling' concept.
1. Housekeeping concept
According to the housekeeping concept, a private household is either:
(a) A one-person household, that is a person who lives alone in a separate housing unit or who occupies, as a lodger, a separate room (or rooms) of a housing unit but does not join with any of the other occupants of the housing unit to form part of a multiperson household as defined below; or
(b) A multiperson household, that is a group of two or more persons who combine to occupy the whole or part of a housing unit and to provide themselves with food and possibly other essentials for living. Members of the group may pool their incomes to a greater or lesser extent.
2. Household-dwelling concept
The household-dwelling concept considers all persons living in a housing unit to be members of the same household, such that there is one household per occupied housing unit. In the household dwelling concept, then, the number of occupied housing units and the number of households occupying them is equal, and the locations of the housing units and house­ holds are identical.
The category 'Persons living in a private household' comprises 'Persons in a family nucleus' and 'Persons not in a family nucleus'. The category 'Persons in a family nucleus' comprises all persons who belong to a private household that contains a family nucleus of which they are a member. 'Persons not in a family nucleus' comprises all persons who either belong to a non-family household or to a family household without being member of any family nucleus in that household.
A non-family household can be a one-person household ('Living alone') or a multiperson household without any family nucleus. The category 'Not living alone' comprises persons that live either in a multiperson household without any family nucleus or in a family household without being member of any family nucleus in that household. Persons who belong to a skip-generation household and who are not member of any family nucleus in that household shall be classified in the optional category 'Persons living in a household with relative(s)'.
The term 'son/daughter' is defined as the term 'child' in the technical specifications for the topic 'Family status'. 'Husband/wife couple' means a married opposite-sex couple.
'Registered partnership' is defined as in the technical specifications for the topic 'Legal marital status'. 'Consensual union' is defined as in the technical specifications for the topic 'Family status'.
The category 'Partners' comprises 'Persons in a married couple', 'Partners in a registered partnership' and 'Partners in a consensual union'.
'Primary homeless persons' are persons living in the streets without a shelter that would fall within the scope of living quarters as defined in the technical specifications for the topic 'Type of living quarters'.

3.4.22 Statistical concepts and definitions - Size of private household

Private households may be defined according to the 'housekeeping concept' , or, if this is not possible, Member States may apply the 'household-dwelling' concept.
1. Housekeeping concept
According to the housekeeping concept, a private household is either:
(a) A one-person household, that is a person who lives alone in a separate housing unit or who occupies, as a lodger, a separate room (or rooms) of a housing unit but does not join with any of the other occupants of the housing unit to form part of a multiperson household as defined below; or
(b) A multiperson household, that is a group of two or more persons who combine to occupy the whole or part of a housing unit and to provide themselves with food and possibly other essentials for living. Members of the group may pool their incomes to a greater or lesser extent.
2. Household-dwelling concept
The household-dwelling concept considers all persons living in a housing unit to be members of the same household, such that there is one household per occupied housing unit. In the household dwelling concept, then, the number of occupied housing units and the number of households occupying them is equal, and the locations of the housing units and house­ holds are identical.
The category 'Persons living in a private household' comprises 'Persons in a family nucleus' and 'Persons not in a family nucleus'. The category 'Persons in a family nucleus' comprises all persons who belong to a private household that contains a family nucleus of which they are a member. 'Persons not in a family nucleus' comprises all persons who either belong to a non-family household or to a family household without being member of any family nucleus in that household.
A non-family household can be a one-person household ('Living alone') or a multiperson household without any family nucleus. The category 'Not living alone' comprises persons that live either in a multiperson household without any family nucleus or in a family household without being member of any family nucleus in that household. Persons who belong to a skip-generation household and who are not member of any family nucleus in that household shall be classified in the optional category 'Persons living in a household with relative(s)'.
The term 'son/daughter' is defined as the term 'child' in the technical specifications for the topic 'Family status'. 'Husband/wife couple' means a married opposite-sex couple.
'Registered partnership' is defined as in the technical specifications for the topic 'Legal marital status'. 'Consensual union' is defined as in the technical specifications for the topic 'Family status'.
The category 'Partners' comprises 'Persons in a married couple', 'Partners in a registered partnership' and 'Partners in a consensual union'.
'Primary homeless persons' are persons living in the streets without a shelter that would fall within the scope of living quarters as defined in the technical specifications for the topic 'Type of living quarters'.

3.4.23 Statistical concepts and definitions - Tenure status of households

The topic 'Tenure status of households' refers to the arrangements under which a private household occupies all or part of a housing unit.
Households that are in the process of paying off a mortgage on the housing unit in which they live or purchasing their housing unit over time under other financial arrangementsare classified under 'Households of which at least one member is the owner of the housing unit'.
Households of which at least one member is the owner of the housing unit and at least one member tenant of all or part of the housing unit are classified under category 'Households of which at least one member is the owner of the housing unit'.

3.4.24 Statistical concepts and definitions - Type of living quarter

'Conventional dwellings' are structurally separate and independent premises at fixed locations which are designed for permanent human habitation and are, at the reference date, either used as a residence, or vacant, or reserved for seasonal or secondary use.
'Separate' means surrounded by walls and covered by a roof or ceiling so that one or more persons can isolate themselves. 'Independent' means having direct access from a street or a staircase, passage, gallery or grounds.
'Other housing units' are huts, cabins, shacks, shanties, caravans, houseboats, barns, mills, caves or any other shelter used for human habitation at the time of the census, irrespective if it was designed for human habitation.
'Collective living quarters' are premises which are designed for habitation by large groups of individuals or several households and which are used as the usual residence of at least one person at the time of the census.
'Occupied conventional dwellings', 'other housing units' and 'collective living quarters' together represent'‘living quarters'. Any 'living quarter' must be the usual residence of at least one person.

3.4.25 Statistical concepts and definitions - Occupancy status

'Occupied conventional dwellings' are conventional dwellings which are the usual residence of one or more persons at the time of the census. 'Unoccupied conventional dwellings' are conventional dwellings which are not the usual residence of any person at the time of the census.
Conventional dwellings with persons present but not included in the census are classified under the category 'Dwellings reserved for seasonal or secondary use'.

3.4.26 Statistical concepts and definitions - Type of ownership

The topic 'Type of ownership' refers to the ownership of the dwelling and not to that of the land on which the dwelling stands.
'Owner-occupied dwellings' are those where at least one occupant of the dwelling owns parts or the whole of the dwelling. 'Cooperative ownership' refers to ownership within the framework of a housing cooperative.
'Rented dwellings' are those where at least one occupant pays a rent for the occupation of the dwelling, and where no occupant owns parts or the whole of the dwelling.

3.4.27 Statistical concepts and definitions - Number of occupants

The number of occupants of a housing unit is the number of people for whom the housing unit is the usual residence.

3.4.28 Statistical concepts and definitions - Useful floor space

Useful floor space is defined as the floor space measured inside the outer walls excluding non-habitable cellars and attics and, in multi-dwelling buildings, all common spaces; or the total floor space of rooms falling under the concept of 'room'.
A 'room' is defined as a space in a housing unit enclosed by walls reaching from the floor to the ceiling or roof, of a size large enough to hold a bed for an adult (4 square metres at least) and at least 2 metres high over the major area of the ceiling.

3.4.29 Statistical concepts and definitions - Number of rooms

A 'room' is defined as a space in a housing unit enclosed by walls reaching from the floor to the ceiling or roof, of a size large enough to hold a bed for an adult (4 square metres at least) and at least 2 metres high over the major area of the ceiling.

3.4.30 Statistical concepts and definitions - Density standard (floor space)

The topic ‘Density standard’ relates the useful floor space in square metres or the number of rooms to the number of occupants, as specified under the topic 'Number of occupants'.
Data report on the density standard measured by the 'useful floor space', or, if not possible, by the 'number of rooms'.

3.4.31 Statistical concepts and definitions - Density standard (number of rooms)

The topic ‘Density standard’ relates the useful floor space in square metres or the number of rooms to the number of occupants, as specified under the topic 'Number of occupants'.
Data report on the density standard measured by the 'useful floor space', or, if not possible, by the 'number of rooms'.

3.4.32 Statistical concepts and definitions - Water supply system

    Information on water supply system was collected in full compliance with Reg. (EC) 1201/2009. Private households were asked if they have a water supply system, if their drinking water comes not from public water utilities or a well but from an indirect source such as a cistern that is refilled periodically, and if the only water available inside the dwelling is not fit to drink.

Availability of hot water (for sanitary purposes in the bathroom and/or kitchen: sanitary hot water) refers only to water that is heated by a permanent system, not on the stovetop or with other systems.

Hot water supply systems are distinguished between those exclusively run by the dwelling’s heating system, those run by a separate system such as a gas- or electric-powered water boiler, and those run entirely or partly by solar panels.

3.4.33 Statistical concepts and definitions - Toilet facilities

    Information on toilet facilities was collected in full compliance with the Reg. (EC) 1201/2009. Toilets refer to fixtures that are permanently connected to a water supply with drainage for waste water, and that are located inside the dwelling or in rooms with independent access.

3.4.34 Statistical concepts and definitions - Bathing facilities

A bathing facility is any facility designed to wash the whole body and includes shower facilities.

3.4.35 Statistical concepts and definitions - Type of heating

"Not stated" category comprises all occupied conventional dwellings with "no heating at all"

A housing unit is considered as centrally heated if heating is provided either from a community heating centre or from an installation built in the building or in the housing unit, established for heating purposes, without regard to the source of energy.

3.4.36 Statistical concepts and definitions - Type of building

The topic 'Dwellings by type of building' refers to the number of dwellings in the building in which the dwelling is placed.

3.4.37 Statistical concepts and definitions - Period of construction

The period of construction has only been surveyed for dwellings in residential buildings.
A residential building is understood to mean:
• a building designed, constructed and used solely for residential purposes: detached houses, villas, cottages, terraced houses, small buildings in residential complexes, etc.;
• a building designed, constructed and used mainly for residential purposes: multi-apartment buildings or apartment blocks with shops (or premises for economic activities) at street level, etc.;
• a building which, though not designed and constructed for residential purposes, over time has undergone a change of use and has become residential.
• a building which, though designed and constructed for residential purposes, over time has undergone a change of use and is currently no longer a residential building, e.g. a residential building which has become the offices of self-employed persons.

The topic 'Dwellings by period of construction' refers to the year when the building in which the dwelling is placed was completed.

3.5 Statistical unit

The EU programme for the 2011 population and housing censuses include data on persons, private households, family nuclei, conventional dwellings and living quarters

3.6 Statistical population

Persons enumerated in the 2011 census are those who were usually resident in the territory of the reporting country at the census reference date. Usual residence means the place where a person normally spends the daily period of rest, regardless of temporary absences for purposes of recreation, holidays, visits to friends and relatives, business, medical treatment or religious pilgrimage

3.7 Reference area

Data are available at different levels of geographical detail: national, NUTS2, NUTS3 and local administrative units (LAU2)

3.8 Coverage - Time

Data refer to the situation in the reporting country at the census reference date (see item 5)

3.9 Base period
4. Unit of measure

Counts of statistical units

5. Reference Period
09/10/2011
6. Institutional Mandate

At national level, Article 50(2) of Legislative Decree No 78/2010, converted with amendments into Law No 122/2010, launched and funded the 2011 General Censuses and established that ISTAT should organise census operations by means of the General Census Plan (PGC, Decision of the President of ISTAT No 6 of 18 February 2011). The PGC sets the guidelines for the planning, organisation and execution of operations relating to the 15th General Population and Housing Census. Relevant circulars were issued to regulate specific operational aspects.

6.1 Institutional Mandate - legal acts and other agreements

At national level: ISTAT and the Statistical Office of the Ministry of the Interior.
At regional level: Regional census offices of ISTAT and the statistical offices of the regions.
At provincial level: Provincial census offices in prefectures.
At municipal level: Municipal census offices.

6.1.1 Bodies responsible

At national level: ISTAT and the Statistical Office of the Ministry of the Interior.
At regional level: Regional census offices of ISTAT and the statistical offices of the regions.
At provincial level: Provincial census offices in prefectures.
At municipal level: Municipal census offices.

6.2 Institutional Mandate - data sharing

Standard text on data ownership by Eurostat

7. Confidentiality
7.1 Confidentiality - policy

The legislation in force guarantees the protection of personal data both in the statistical field and for other purposes regulated by the law, ensuring that they are constantly and effectively protected.

The main legislative texts in this field are:

a) Legislative Decree No 322/1989, which established the national statistical system (SISTAN) and regulated ISTAT's activities;

b) Legislative Decree No 196/2003 and subsequent implementing provisions for the general protection of personal data.

The law establishing the 15th General Population and Housing Census (Article 50 of Legislative Decree No 78/2010) confirmed and further specified the arrangements for protecting the confidentiality of personal data, calling on ISTAT to identify the technical arrangements to be adopted by local survey bodies. These instruments, for everybody involved in carrying out the survey and according to their functions and the organisational arrangements adopted, laid down specific provisions to ensure the absolute secrecy of personal data at all stages of collection, storage and transmission.

Any failure to comply with the provisions laid down was punishable by administrative, civil or criminal penalties, according to the seriousness of the violation found.

ISTAT has continuously monitored full compliance with all of the provisions laid down, by technological means and by means of suitably qualified internal staff.

7.2 Confidentiality - data treatment

The personal identification details of individuals were physically separated from the rest of the socio-demographic information gathered by means of paper questionnaires, and delivered and processed independently in order to ensure confidentiality in relation to the contractors responsible for transport and the recording of data on magnetic media.

Confidentiality in the treatment of census data collected by means of the online questionnaire was based on the encryption of the sensitive information requested. In particular, data was secured through the development of software applications within ISTAT which ensured an encrypted channel of communication, and through the purchase of an additional module of the DBMS, which ensured that the data contained in the database was stored in an encrypted fashion.

No limitation is imposed in the dissemination of survey macrodata, while the microdata were disseminated in accordance with the General Census Plan (see 10.4. Dissemination format - microdata access).

8. Release policy
8.1 Release calendar

Data are made available 27 months after the end of the reference period (March 2014)

8.2 Release calendar access
8.3 Release policy - user access

- data published in the institute's data warehouse (I.Stat)
- press releases at www.istat.it and provided to the media
- specific products requested via the institute's contact centre
- anonymous microdata provided and made available to users

9. Frequency of dissemination

Data on population and housing censuses are disseminated every decade

10. Dissemination format
10.1 Dissemination format - News release

http://www.istat.it/it/censimento-popolazione/popolazione-2011

10.2 Dissemination format - Publications

Publications in paper form containing further thematic information are provided

10.3 Dissemination format - online database

I.Stat (http://dati-censimentopopolazione.istat.it/)

10.4 Dissemination format - microdata access

- The communication of census data to the bodies of the National Statistical System, in accordance with the legislation in force on confidentiality, is carried out by ISTAT in accordance with the provisions of Article 50 of DL No 78 of 31 May 2010 and according to the methods laid down in Article 8 of the Code of ethics and good conduct regarding the processing of personal data for statistical and scientific research purposes within the National Statistical System and Comstat Directive No 9 of 20 April 2004.
- With regard to the census bodies, the elementary data (without information identifying individual survey units) for the relevant territory and necessary for the carrying out of institutional functions, were communicated, on request to ISTAT, in accordance with the aforementioned Article 50 and the legislation on the processing of personal data for statistical purposes.
- sample collections of individual anonymised data (standard files, files for research)

10.5 Dissemination format - other

- Adele Laboratory (archive of elementary data) in the institute
- ad hoc products on request

11. Accessibility of documentation
11.1 Documentation on methodology

11.2 Quality management - documentation

12. Quality management
12.1 Quality assurance

On the ISTAT website (www.istat.it):

ISTAT has created quality assurance instruments consistent with its mission and fully in accordance with Eurostat's reference framework for the European statistical system.

They are the result of a long process involving ISTAT and others.

The following instruments established by ISTAT to improve the quality of statistical processes and products can be of interest and use to the bodies of the National Statistical System, researchers and users of data in general:

- Guidelines on the quality of statistical processes (http://www.istat.it/it/strumenti/qualit%C3%A0-dei-dati/linee-guida);

- Information system on the quality of statistical production processes (SIQual - http://siqual.istat.it/);

- Audit (http://www.istat.it/it/strumenti/qualit%C3%A0-dei-dati/audit).

For further information see the National Institute of Statistics' quality policy.

http://www.istat.it/it/istituto-nazionale-di-statistica/qualit%C3%A0

12.2 Quality management - assessment

The process is monitored by means of a range of activities aimed at the timely identification of errors so that the appropriate corrective measures can be taken to restore the correct operation of the system.

Monitoring of fieldwork. Fieldwork activity involved a dedicated monitoring system (SGR – Survey Management System) which traced deliveries of questionnaires to households, spontaneous return to municipalities of questionnaires completed by households according to return method (online completion, postal delivery, delivery to municipalities' contact points) and data regarding contacts and collection by municipal enumerators in the case of households late in returning questionnaires. The system was designed to minimise the risks arising from cooperation between the provider of the postal delivery and return service for questionnaires (Poste Italiane) and the bodies responsible for the management of the fieldwork. This enables daily, weekly and monthly reports to be produced for use by the various stakeholders responsible for surveying: enumerators, municipal census offices, ISTAT.

Monitoring of optical reading A contractor was responsible for monitoring the optical reading of questionnaires provided in paper form, using a traditional sample check of product quality by batches of material delivered. The parameters controlled were the percentages of errors for variables classified as: pre-coded, numerical, alphanumerical and identification codes. Similar controls were carried out on alphanumeric variables coded by Postel (Municipality and Foreign State). The control was carried out by repeating the recording of a sample of characters from a randomly chosen batch selection and comparing them with the characters recorded by the service provider. Batches with error rates not statistically greater than the maximum tolerated in the contract were accepted by ISTAT and sent for subsequent processing. Batches which did not pass the controls for any of the parameters checked were rejected and subjected to further processing for those parameters. Financial penalties were set for each delay in processing caused by errors leading to the rejection of batches of material and the slowing of activities.

Validation of data. The validation of data was carried out in order to check that the surveying of households, the imputation and correction of microdata and the re-weighting of the sample according to known totals did not render the macrodata inconsistent with known external sources. To this end, two data validation activities were carried out, the first of which was before the publication of the legal population and the second before the dissemination of hypercubes of interest both nationally and to Eurostat. The activities during the first stage of validation were aimed at checking the coverage of the census and were based on a micro and macro comparison with the data in the population registers managed by municipalities and on an analysis of the distribution of certain process indicators collected by means of SGR. Inquiries on and inspections of the activities carried out by municipal census offices were aimed at checking and rectifying any inconsistencies between personal data and census data. A second validation stage was aimed at the accuracy of the data collected and consisted of comparing a selected range of census macrodata calculated at different regional levels with the corresponding figure obtained from other administrative or statistical sources. As a result of significant discrepancies found between sources, systematic errors were identified and rectified in the imputation and correction procedures, and the system of known totals adopted to determine the final sampling weights.

12.2.1 Coverage assessment

The 2011 General Population and Housing Census was assessed in terms of coverage of individuals residing in households, by means of the post-census coverage survey described in point 12.2.2. Other census coverage assessment activities, aimed at checking the quality of processes and the timely correction of errors, are described in point 12.2 under the heading ‘validation of data’.

12.2.2 Post-enumeration survey(s)

The main aim of the PES (post-enumeration survey) is to estimate the number of individuals genuinely and habitually resident during the reference period of the 15th General Population and Housing Census (9 October 2011) and the rate of coverage, defined as the ratio between the number of individuals surveyed in the Census (excluding communal establishments) and the number of individuals genuinely resident. The sampling is a two-stages one, with stratification of primary units (252 municipalities sub-divided into self representative and non self representative) and of secondary units (around 2.500 census areas). The survey is designed in such a way as to ensure independence between the two surveys (Census and PES). Households and individuals habitually living in dwellings in the census areas selected for the sample at the time of the PES are surveyed. The survey was carried out from April to July 2012 and involved around 1.200 surveyors selected amongst the 'best' of the Census (naturally, each of them was assigned to an area different to the one in which they worked for the Census). The PES covered around 329.000 eligible individuals; the survey is followed by detailed Record Linkage stage and the application of a complex estimation model (Dual System of the ONS approach). The PES data will also be used to assess the simple response variance relating to the main variables included in the census survey questionnaire.

13. Relevance
13.1 Relevance - User Needs
p>The census data disseminated by Eurostat are addressed to policy makers, researchers, media and the general public.
13.2 Relevance - User Satisfaction

No user satisfaction surveys are carried out. User inquiries are handled by the Eurostat User Support service.

13.3 Completeness

Depends on the availability of data transmitted by the National Statistical Institutes.

14. Accuracy
14.1 Accuracy - overall
14.1.1 Overall accuracy - Usual residence

There are no particular reasons for data unreliability for this topic

14.1.2 Overall accuracy - Sex

There are no particular reasons for data unreliability for this topic

14.1.3 Overall accuracy - Age

There are no particular reasons for data unreliability for this topic

14.1.4 Overall accuracy - Marital status

There are no particular reasons for data unreliability for this topic

14.1.5 Overall accuracy - Family status

Data for couples of the same sex in Italy are an underestimate and refer only to couples of the same sex who chose to declare themselves as such. Many people in the same situation preferred not to do so, despite ISTAT's recommendations 

There are no particular reasons for data unreliability for this topic

14.1.6 Overall accuracy - Household status

Data for couples of the same sex in Italy are an underestimate and refer only to couples of the same sex who chose to declare themselves as such. Many people in the same situation preferred not to do so, despite ISTAT's recommendations.

There are no particular reasons for data unreliability for this topic

14.1.7 Overall accuracy - Current activity status

There are no particular reasons for data unreliability for this topic

14.1.8 Overall accuracy - Occupation

There are no particular reasons for data unreliability for this topic

14.1.9 Overall accuracy - Industry

There are no particular reasons for data unreliability for this topic

14.1.10 Overall accuracy - Status in employment

There are no particular reasons for data unreliability for this topic

14.1.11 Overall accuracy - Place of work

There are no particular reasons for data unreliability for this topic

14.1.12 Overall accuracy - Educational attainment

There are no particular reasons for data unreliability for this topic

14.1.13 Overall accuracy - Size of the locality

There are no particular reasons for data unreliability for this topic

14.1.14 Overall accuracy - Place of birth

There are no particular reasons for data unreliability for this topic

14.1.15 Overall accuracy - Country of citizenship

There are no particular reasons for data unreliability for this topic

14.1.16 Overall accuracy - Year of arrival in the country

There are no particular reasons for data unreliability for this topic

14.1.17 Overall accuracy - Residence one year before

There are no particular reasons for data unreliability for this topic

14.1.18 Overall accuracy - Housing arrangements

There are no particular reasons for data unreliability for this topic

14.1.19 Overall accuracy - Type of family nucleus

There are no particular reasons for data unreliability for this topic

14.1.20 Overall accuracy - Size of family nucleus

There are no particular reasons for data unreliability for this topic

14.1.21 Overall accuracy - Type of private household

There are no particular reasons for data unreliability for this topic

14.1.22 Overall accuracy - Size of private household

There are no particular reasons for data unreliability for this topic

14.1.23 Overall accuracy - Tenure status of households

There are no particular reasons for data unreliability for this topic

14.1.24 Overall accuracy - Type of living quarter

There are no particular reasons for data unreliability for this topic

14.1.25 Overall accuracy - Occupancy status

There are no particular reasons for data unreliability for this topic

14.1.26 Overall accuracy - Type of ownership

There are no particular reasons for data unreliability for this topic

14.1.27 Overall accuracy - Number of occupants

There are no particular reasons for data unreliability for this topic

14.1.28 Overall accuracy - Useful floor space

There are no particular reasons for data unreliability for this topic

14.1.29 Overall accuracy - Number of rooms

There are no particular reasons for data unreliability for this topic

14.1.30 Overall accuracy - Density standard (floor space)

There are no particular reasons for data unreliability for this topic

14.1.31 Overall accuracy - Density standard (number of rooms)

There are no particular reasons for data unreliability for this topic

14.1.32 Overall accuracy - Water supply system

There are no particular reasons for data unreliability for this topic

14.1.33 Overall accuracy - Toilet facilities

There are no particular reasons for data unreliability for this topic

14.1.34 Overall accuracy - Bathing facilities

There are no particular reasons for data unreliability for this topic

14.1.35 Overall accuracy - Type of heating

There are no particular reasons for data unreliability for this topic

14.1.36 Overall accuracy - Type of building

There are no particular reasons for data unreliability for this topic

14.1.37 Overall accuracy - Period of construction

There are no particular reasons for data unreliability for this topic

14.2 Sampling error
14.3 Non-sampling error
15. Timeliness and punctuality
15.1 Timeliness

- 24/02/2014 HC55, HC56, HC59, HC40, HC45
- 13/03/2014 HC39, HC46
- 17/03/2014 HC47, HC48
- 20/03/2014 HC49, HC57, HC05, HC52, HC58, HC51, HC42, HC50, HC18, HC01, HC02, HC07
- 21/03/2014 HC34, HC35, HC38, HC06
- 25/03/2014 HC08, HC12, HC13, HC25, HC33, HC36, HC37, HC44, HC26, HC27, HC28, HC09, HC29, HC03, HC30, HC23
- 27/03/2014 HC04, HC53, HC60
- 28/03/2014 HC22, HC43, HC32, HC21, HC31, HC14, HC54, HC15, HC16, HC19, HC10, HC11, HC17, HC20, HC24, HC41

15.2 Punctuality
16. Comparability
16.1 Comparability - geographical

- 24/02/2014 HC55, HC56, HC59, HC40, HC45
- 13/03/2014 HC39, HC46
- 17/03/2014 HC47, HC48
- 20/03/2014 HC49, HC57, HC05, HC52, HC58, HC51, HC42, HC50, HC18, HC01, HC02, HC07
- 21/03/2014 HC34, HC35, HC38, HC06
- 25/03/2014 HC08, HC12, HC13, HC25, HC33, HC36, HC37, HC44, HC26, HC27, HC28, HC09, HC29, HC03, HC30, HC23
- 27/03/2014 HC04, HC53, HC60
- 28/03/2014 HC22, HC43, HC32, HC21, HC31, HC14, HC54, HC15, HC16, HC19, HC10, HC11, HC17, HC20, HC24, HC41

16.2 Comparability - over time
17. Coherence
17.1 Coherence - cross domain

Figures provided by the National Statistical Institutes in the framework of the 2011 Population and Housing Census may differ from those transmitted in other statistical domains due to the cross domain differences in definitions and methodologies used.  For additional information please see metadata specific to each domain.

17.2 Coherence - internal

Internal coherence is assured by regulations defining breakdowns and definitions of topics (Regulation (EC) No 1201/2009, Regulation (EU) No 519/2010, Regulation (EU) No 1151/2010)

18. Cost and Burden

The overall cost is 604 million, including personnel costs.

Italy's 15th General Population and Housing Census saw many significant methodological, technical and organisational innovations introduced in order to reduce the organisational impact on public authorities, to speed up the dissemination of the final data and to reduce the statistical burden on households to a minimum.
For the first time in the history of Italian censuses, questionnaires were delivered to households by post. Respondents were able to choose between completing the questionnaire online or completing a paper questionnaire and returning it to a Post Office or municipal collection centre, in each case being provided with a receipt of delivery.
In order to reduce burdens on citizens, some information of a socio-economic nature was gathered on a sample basis. To this end, two types of questionnaire were provided: a short version with few questions, and a full version which, as well as the questions contained in the short version, included those needed to obtain the other variables of the survey plan.
The short version, with a limited number of questions, gathered all of the most important demographic and socio-economic data (educational attainment, status in employment, daily travel within the municipality or between municipalities for reasons of work or study). The full version included, in addition to the variables contained in the short version, further questions regarding education, work and commuting, as well as certain questions (not obligatory) regarding any difficulties (visual, hearing, mobility, cognitive) faced in daily activities. The variables in both the short form and the long form of the questionnaire were gathered from the entire Italian population. The full version of the questionnaire was delivered to all resident households in municipalities with fewer than 20.000 inhabitants on 1 January 2010, and to some resident households in municipalities with populations above that threshold and in provincial capitals. The short version of the questionnaire was delivered to the remaining population residing in municipalities with more than 20.000 inhabitants and in provincial capitals.
Finally, particular attention was paid to the foreign population, by means of organisational and communication arrangements intended to encourage them to participate in the census.

19. Data revision
19.1 Data revision - policy
19.2 Data revision - practice

The cubes HC1, HC2, HC3, HC4, HC5, HC6, HC7, HC8, HC9, HC10, HC11, HC12, HC13, HC14, HC15, HC16, HC17, HC18, HC19, HC20, HC21, HC22, HC23, HC24, HC25, HC26, HC27, HC28, HC29, HC30, HC31, HC32, HC33, HC34, HC35, HC36, HC37, HC38, HC39, HC41, HC42, HC43, HC44, HC46, HC47, HC48, HC49, HC50, HC51, HC52, HC53, HC54, HC57, HC58 and HC60 will be revised by 30 September 2014. Since the revision will be carried out following a recalibration of the system of sampling weights, variations compared to the cubes currently available will be very small.

20. Statistical processing
20.1 Source data
20.1.1 List of data sources
20.1.1.1 List of data sources - data on persons

Data source: 2011 General Population and Housing Census

20.1.1.2 List of data sources - data on households

Data source: 2011 General Population and Housing Census

20.1.1.3 List of data sources - data on family nuclei

Data source: 2011 General Population and Housing Census

20.1.1.4 List of data sources - data on conventional dwellings

Data source: 2011 General Population and Housing Census

20.1.1.5 List of data sources - data on living quarters

Data source: 2011 General Population and Housing Census

20.1.2 Classification of data sources
01.Conventional censuses
20.2 Frequency of data collection

Data on population and housing censuses are collected every decade, in a reference year that falls during the beginning of every decade

20.3 Data collection

Census questionnaires have been tested by means of both a Pilot Survey and a cognitive test. This last has been conducted in collaboration with the Institute of Cognitive Sciences and Technologies (ISTC) of the Italian National Research Council (CNR), in order to assess the cognitive difficulties in questionnaires’ comprehension and to identify possible improvements in questions’ wording and sequence, while the Pilot Survey has been held in order to test the possible use of technological and methodological innovations designed to solve problems related to conventional censuses. Alternative enumeration strategies were tested on a number of municipalities with different characteristics and, as a result, a composite strategy, differentiated according to the municipality size, was put in place for the census. Its basic features were the use of Population Registers as enumeration lists; the mail out of questionnaires (based on households names and addresses drawn from population registers), and the use of a simultaneous multi-mode (electronic and paper questionnaires, with a multi-return option for paper questionnaires) data collection system which included: a) Internet; b) return at any post offices in Italy; c) return to Municipal Collection Centres.
Questionnaires were sent to respondents together with a letter and guidelines, while video tutorials were available on the census website and a free toll number was provided to give respondents support with filling in the questionnaires. Specific follow-up procedures were implemented in case of non-response, namely enumerators were sent on the field for the targeted recovery of non-response, and they had to pay at least 3 visits to each household before declaring it not enumerated. In order to allow respondents the maximum flexibility, the 3 automatic response options were still in place, at the time enumerators were sent on the field for the targeted recovery of non-response.
In order to further reduce the burden on respondents a short form/long form strategy has been adopted in the largest municipalities: namely, in the smallest municipalities the long form was administered to the whole population while in the ones with at least 20.000 inhabitants the long form was administered to a third of the households and the short one to the remaining two thirds. The allocation of the topics to the two forms was based primarily on EU census dissemination programme. In order to manage such a complex and diverse enumeration strategy, Istat developed a highly integrated web information system (SGR) that supported all of the different phases of the enumeration process guided and supported census operators.

20.4 Data validation

The data production process was structured on the basis of a series of steps forming a controlled workflow. The data collected was divided into thematic blocks, and for each of them the production process was essentially in two stages: the control and correction stage and the validation stage. These two components of the production process involved a single control process and a validation support application enabling transition between the correction, control and validation stages.
The control and correction procedures adopted followed standard methodologies and their effects were analysed during the validation stage. The validation stage was based on comparison with previously identified benchmark sources. Where possible, the validation was carried out in two stages: the first, known as 'pre-validation', identifies, by means of specific analysis procedures, the macrodata (aggregated data for predetermined dissemination, e.g. LAU 2) for in-depth review; the second, carried out interactively by revisers through the use of reports and with the support of thematic experts, analyses and validates the macrodata identified in stage 1.

20.5 Data compilation

Online completion of questionnaire. Online questionnaire completion enabling households to provide data via a web browser. Interactive controls of questionnaires completed online to check the completion path and the completion of the main questions.

Optical reading and manual recording. Optical reading of questionnaires returned in paper form. Optical reading contracted out by international invitation to tender. Questionnaires for scanning collected by the contracting company from municipalities and scanned in the company’s centres. Scanning of characters subject to video control with operator if the automatic interpretation programme found a low probability of assignment of the value. Preliminary quality control of formats for all questionnaires, where necessary sent for manual recording. All questionnaires concerning communal establishments were sent for manual recording.

Coding of text variables. In the case of questionnaires delivered in paper form, and in the fields in which information was collected in free text format, the variables ‘Municipality’ and ‘Foreign State’ were automatically coded with the assistance of manual operators. Coding was carried out by the contractor responsible for the optical reading of paper questionnaires. Subsequent control activities in ISTAT were carried out by means of automatic control procedures based on algorithms for the coding of text variables and on interactive controls.

Removal of duplicated individuals. Two circumstances in which records might be duplicated were dealt with:

Households or individuals sending the questionnaire twice, once via the internet and once by post, identified by means of the single code and corrected on the basis of the version delivered online;

Households or individuals responding twice by means of different questionnaires, in the same or in different municipalities, identified by probabilistic record linkage of individuals' personal data. Corrected by removing one of the two records in accordance with deterministic rules giving precedence to the unification of families over the official residence of individuals.

Reassembly of information for questionnaires completed in paper format. In order to guarantee respondents' confidentiality in relation to providers of postal and recording services, the part of household questionnaires containing members' personal data was physically separated from the rest of the questionnaire and processed differently. The two parts of the questionnaire were reassembled by means of a single identification code after being obtained in digital form. As a result of errors in the recording of single identification codes, some questionnaires were not reassembled and were matched by means of other information (municipality code, family code, date of birth, sex, citizenship). In the case of individuals for whom it was not possible in any way to identify their corresponding questionnaire, the entire record was subjected to imputation.

Identification of households and families. In relation to this point, in the particular case of families, these were identified by means of complex algorithms which, on the basis of the variables family relation, age, sex and marital status, made it possible to identify the presence of couples and relationships within the household.

Control and correction of microdata. Missing data regarding date of birth, sex and citizenship corrected by means of municipal register data. For the remaining variables, the imputation of missing or inconsistent values was carried out by probabilistic, data driven, deterministic or interactive methods, taking account of the rules on compatibility between household members.

Preparation of sampling weights bound to known totals. The application of bound weighting procedures to determine sampling weights of individuals surveyed by means of the long form of the questionnaire. Links were applied in accordance with around 2.000 totals relating to macrodata disseminated via the national publication plan and determined on the basis of the information collected on the entire population

20.6 Adjustment
21. Comment