1991 Census Appendix 20


(Source: 1991 Census Definitions)

Absent Households


In the 1981 Census residents in wholly absent households ie no person present in the household on census night, were excluded from the enumeration at their usual address. In an attempt to improve coverage of the 1991 Census, all households absent on Census night were left a form with a letter asking them to complete the form on their return home. For those absent households for whom a completed form was not received, certain data are imputed using some basic information (eg number of persons living at the address and details of the accommodation) collected by the enumerator and also drawing on information from similar absent households which did complete and return census forms. See also 1991 Census definitions p.6.

Absent Residents


Any person who is usually a member of the household but on Census night was absent on holiday, at school or college, or for any other reason, even if they are being included on another census form elsewhere.



The main source of information on accommodation is taken from Panel A of the Census form and Question H2. Use is also made of the information provided by the building bracket linking household spaces in a converted or shared house, bungalow or flat (Panel A boxes 7 or 8).



An adult is any person who is not a dependent child.

Census Form


Each household was enumerated on a 12 page H form (W form in Wales). The names of persons spending Census night in communal establishments and on HM Ships and other vessels were listed on an L form with each person enumerated separately on an I form (Iw form in Wales). Enumerators had the responsibility for recording certain housing information (Panel A on the H form) and making an assessment of the nature of the accommodation if it was not occupied on Census night. As in 1981, the form filler was instructed to include on the Census form 'every person who spends Census night in this household, including anyone staying temporarily'; 'any other people who are usually members of the household but on Census night are absent on holiday, at school or college, or for any other reason, even if they are being included on another census form elsewhere'; 'anyone who arrives here on Monday April 22nd who was in Great Britain on the Sunday and who has not been included as present on another census form'; and 'any newly born baby born before April 22nd, even if still in hospital'.

Census Night


April 21-22nd 1991.

Communal Establishments


The term covers all establishments in which some form of communal catering is provided. Such establishments were enumerated using the L form on which were listed the names of all persons present on Census night together with individual (I) forms containing the relevant census questions.

In 1981 the population in communal establishments(then known as non-private households) included campers with communal catering and persons sleeping rough.

In 1991 all those present in the establishment on Census night and all who arrived on April 22nd who were not included as present on a census form elsewhere, were listed. The names of any non-resident staff, on duty on the premises on Census night were not required to be listed.

See also 1991 Census Definitions, Chapter 4, p. 12-15.


1. Persons quoting a LS date of birth enumerated in a Communal Establishment are included in the LS sample.

2. No double enumeration in Communal Establishments is accepted by census processing. In such situations, eg resident in a Communal Establishment but in hospital on Census night, the form processed would be that completed where the person was on Census night.

De facto


All persons enumerated in a household on Census night.

De jure


All persons, present or absent on Census night, usually resident in a household.

Dependent Child


Persons aged 0-15 in a household; or persons aged 16-18, never married, in full time education and economically inactive. The additional qualification 'and economically inactive' has been added to the 1981 Census definition, which also included persons aged 19-24 who were also never married and classified as a student from the question on economic activity.



Defined as 'structurally separate accommodation.' See also 1991 Census Definitions, Chapter 5, p.16-26.

Economic Activity


The general topic of economic activity covers a wide range of census characteristics including both those obtained directly from questions on the Census form, such as economic position, employment status and occupation, and others which are derived by combining answers to these questions, for example, social class and socio-economic group, which are derived from occupation and employment status.

All persons aged 16 or over at the time of the Census were asked Question 13 which provides information on economic position and employment status. Subsequent questions were addressed only to those persons who were either in paid employment in the week before Census day, or who had had a paid job within the previous ten years. In cases of multiple ticking at Question 13 up to three codes are entered on the computer file. The three lowest numbered boxes ticked are given priority except for boxes 5 (On a Government Employment or Training Scheme) and 8 (At school or in other full time education) which take precedence over all other boxes.

When interpreting the full 12 fold 'Economic position/Employment status' classification, Economically inactive students (Category 9) are those allocated a primary code of 8, and no other boxes 1-4 were ticked. Persons who ticked any box 1-4 in addition to box 8 are separately identified as 'Students, economically active' (Category 8), as well as being included in the appropriate economically active category. Those describing themselves as being on a government scheme are coded to box 5 which takes priority over all other boxes. 'Other inactive comprises persons looking after the home or family, or for whom the last box was ticked and are not reallocated to another category, including persons of independent means.

Question 13 on the 1991 Census form attempts to obtain the same information that was asked for in two separate questions in 1981. Question 10 on the 1981 form had just two 'persons in employment' boxes, which distinguished only between persons with a full time and a part time job. The information on employment status (whether a person was working for an employer or was self employed with/without employees) was obtained from a separate question, Question 13.

The introduction of economically active students in categories 1-4 is also a change from 1981, introduced to follow International Labour Organisation definitions adopted in the early 1980's.

The 1991 question allows for persons on government employment and training schemes to be identified. The 1981 question on employment status included a box for 'apprentice or articled trainee'. See also 'Hours'.

Educational Level


Qualifications obtained over the age of 18 (see also Qualified Manpower) are grouped into three Educational Levels.

Level a - higher degrees of UK standard

Level b - first degrees and all other qualifications of UK first degree standard; and

Level c - qualifications that are (i) generally obtained at 18 and over, (ii) above GCE 'A' level standard; and (iii) below UK first degree standard.

A Qualified Person is one who holds at least one qualification at level a, b or c. Persons holding more than one qualification are generally analyzed by the highest qualification; if two or more qualifications of the same (highest) level are held, the one most recently obtained is used. See Also 1991 Census Appendix 10.

Employment Status


Question 13 used to provide detail on employment status since there was no separate question. Categories for the self employed were included in the Question 13. Information on managers/supervisors is obtained from the occupation question. Persons on a government employment or training scheme are classified as economically active - in employment.

Ethnic Group


Answers to this question were assigned to one of 35 codes. The full classification incorporates each of the 7 pre-coded categories from the question, plus another 28 derived from any multi-ticking of boxes and the written descriptions given in the 'Black-Other' and 'Other ethnic group' boxes. Written descriptions which were the same, or had the same meaning, as one of the pre-coded categories were assigned to the relevant pre-coded groups.



Answers to the questions on age, sex, marital status, long term illness and relationship in household (Question 5) were used to classify households and groups of individuals into families. The 'relationship to the first person entered on the Census form' question differs from that followed in 1981 only in that cohabitant replaces the former de facto spouse (derived from write in answers), and that additional codes are introduced for child of cohabitant and cohabitant of son/daughter in an attempt to identify 'hidden' families within households. The Other unrelated, category, now includes domestic servants who were separately coded in 1981. See also 1991 Census definitions p. 37.

Family Unit Type


A computer algorithm was used to allocate individuals within households to a detailed family type classification. The algorithm also defines the number of family units within a household, the relationship of each unit to the head of the household,and the generation within the family unit to which the individual belongs. in any family unit within a household where there are two generations, the younger generation must be single (never married) and have no obvious partner or offspring. When a person in a younger generation, has or can be shown to have had, a relationship to a person other than their parent/s, that person is not placed in the same family unit as his or her parent/s.

NOTE: The following terms are used in relation to family composition.

Head of Household: See under 'H'.

Dependent Child: Is a person in the second generation of a family. There is no age limit to the term 'child'.

Non-dependent child: is any person in the second generation of a family who is not a dependent child.

Head of family: is generally taken to be the head of household if the family contains the head of household, otherwise,

- in a couple family, the head of family is the first member of the couple on the form;

- in a lone parent family, the head of family is the lone parent; or

- a no family person ie non-dependent person can be treated as head of family.

Family size: is the number of residents in a family as defined above. No person can belong to more than one family.

Head of Household


It should be noted that in 1991 the H form was addressed 'to the Head or Joint Head or members of the Household aged 16 or over' (thus allowing for households with no head). Furthermore, the question on relationship in household asked for the relationship of the second and subsequent persons to the person entered in the first column on the form. For statistical purposes the 100% processed Census tables, the head of household is usually taken to be the person entered in the first column. See also 'Household Composition'.

Hours Worked


Although a question on hours worked was included in the 1971 Census, this item was dropped from the 1981 Census form and replaced with additional full-time/part time job boxes. A question on hours usually worked in a persons main job was re-introduced in the 1991 Census, as well as retaining the full-time/part-time categories in the economic activity question. the maximum number of hours worked to be recorded is 99, hours worked in excess of 99 are coded as 99. Fractions of an hour are rounded to the nearest even number.

Full time work: 31 hours or more a week.

Part time work: 30 hours or less a week.

Household Composition


Uses the answers to the questions on age, sex, marital status and long term illness for each person in the household. A household is either one person living alone or a group of people, who may or may not be related, living or staying temporarily t at the same address, with common housekeeping. As in 1981, enumerators were instructed to treat a group of people as a household if there was any regular arrangement to share at least one meal, including breakfast, a day or if the occupants shared a common living or sitting room. The occupants of one room accommodation or a caravan are treated as a single household.

The head of household is regarded as the person entered in the first column of the form, provided that person was aged 16 years or over and usually resident at the address of enumeration. If one of these conditions was not met, the first person aged 16 or over to be entered on the form and recorded as usually resident at the address of enumeration was coded as the head. In the last resort the oldest resident aged under 16 was taken as the head. No head was identified in households consisting entirely of visitors (same as 1981).

Household Dependent Type


An additional household dependent type classification has been introduced for the 1991 Census, and is defined in terms of dependents and non-dependents in the household. in this classification a dependent is either a dependent child or a person who both has a limiting long term illness and whose economic position is either 'permanently sick' or 'retired'.

A non-dependent is any person who is not a dependent.

Household Space


The accommodation available for a household. Based on information obtained from Panel A, Question H2 and H4.

Unshared converted accommodation is a household space with its room(s) including a bath or shower, WC and kitchen facilities behind its own private door. Unshared not self contained accommodation is identified by Panel A box 7, Question H2 box 2 (bedsit) or box 4. This latter group is further sub-divided into two household space types - those with exclusive use of bath/shower and inside WC (flat) and those without exclusive use of bath/shower and inside WC (rooms).

Shared dwellings comprise two or more household spaces sharing an entrance into the building that are not self contained.

Unattached spaces are household spaces also sharing an entrance into the building but where they are the only one not self contained.

Where not self contained accommodation is unoccupied on Census night and no information on amenities is available to the enumerator/ the accommodation is classified as not self-contained unoccupied.

Because of a basic change in the definition of self-contained accommodation in 1991, it is not possible to compare accurately 1991 and 1981 statistics on self contained and not self-contained accommodation. In 1981 self-contained accommodation required a household sharing an entrance from outside the building with one or more other household(s) to have its own rooms, not including a bathroom or WC, enclosed behind its own front door inside the building. For 1991 the definition was changed to require the rooms and kitchen facilities, bath or shower, and inside WC, to be contained behind the 'private' door.

In 1981, purpose built flats (categories 4 and 5 of the 1991 household space type classification) were counted as a single group 'in a purpose built block of flats or maisonettes'. The separate 1991 categories of detached, semi detached and terraced were only identified in Scotland in 1981. In England and Wales in 1981 these were included with accommodation in converted or shared houses, bungalows or flats as a single group 'household spaces in permanent buildings with separate entrance from outside the building.



The industry in which a person is engaged is determined by the business or activity in which his or her occupation is followed. The industrial classification has regard only to the nature of the service or product to which the labour contributes.

Industry codes are assigned, as far as possible, by reference to lists from the Dept. of Employment which give names and addresses of employers by industry code. Where the employer's name is not listed a code is allocated based on information given in the description of the employer's (or self-employed person's) business.

There has been no subsequent revision to the 1980 Standard Industrial Classification which comprises the full range of industries grouped into 10 divisions each denoted by a single digit. The Divisions are divided into 60 Classes, each denoted by the addition of a second digit, and divided further into 222 Groups and 334 Activities by the addition of third and fourth digits. Census industry coding is based on the Activity heading level with some exceptions where it is not possible to distinguish separate activities/subdivisions of activities. See also 1991 Census definitions p.30-40, and 1991 Census Appendix 7.

Lone Parent Family


A father or mother together with his or her never married child(ren).

Marital Status


Single persons are those who have never married - bachelors and spinsters.

Married, first marriage, persons are those whose first marriage has not ended by divorce or death of a spouse.

Re-married persons are those who have married again after their first or subsequent marriage(s) ended in divorce or death of a spouse and who were still married at the time of the Census.

Widowed and divorced persons are those whose most recent marriage ended respectively, through the death of a spouse or divorce. Persons who were separated but not divorced from their spouse are classified as either married, first marriage, or re-married.

The question in England and Wales is unchanged from that asked in 1981.



The identification of a migrant is based on answers to the questions on usual address, and address one year before the Census. The question is unchanged from the 1981 Census.

A migrant within one year preceding the Census is a person with a different usual address one year ago to that at the time of the Census.

A migrant household is a household whose head is a migrant.

A wholly moving household is a household all of whose resident members aged one year and over were migrants with the same postcode of usual residence one year before the Census. Children aged under one are included as members of wholly moving households.

Multiple Enumerations


Reflects those situations where a LS member is entered on more than one census form. May be either a simple present/absent pair or complex multiple enumeration.

The LS member's Record Type 41 contains single enumerations, 'present' records from simple present/absent pair multiple enumerations and 'chosen' records from complex multiple enumerations. The LS member's Record Type 43 (Absent Usual Residents file) contains 1991 Census multiple enumeration records not included in Record Type 41. These are 'absent' records from simple present/absent pair multiple enumerations and 'not chosen' records from complex multiple enumerations. There may be more than one 'not chosen' record in a complex multiple enumeration.

The variable HISCEN91 on the LS member's Core record contains two codes, 2 and 3, which indicate whether the 1991 Census record is a multiple enumeration or not, and its degree of complexity. Most Record Type 43s are associated with HISCEN91=2; approximately 3 % of records will have HISCEN91=3. HISCEN91=1 is never found with Record Type 43.



The occupation of a person defines the kind of work performed; this generally defines the assignment to an occupation group. The nature of the factory, business or service in which the person is employed has no bearing on the classification of the occupation, except to the extent that such information may clarify the nature of the duties. Occupation codes are allocated from the write-in answers at Question 15, which was asked of all persons who had had a paid job either in the week before the Census or within the previous ten years. A new Standard Occupational Classification (SOC) replaced both the 1980 Classification of Occupations and the Classification of Occupations and Directory of Occupational Titles (CODOT). The main concept of the new SOC was to classify jobs as opposed to classifying persons. The classification is based entirely on information about the type of work done, as indicated by the job title and description, and unlike its 1980 predecessor takes no account of ancillary information on employment status, such as whether someone is self employed, which is not always available from non census sources.

The format of the classification is hierarchical, offering different levels of aggregation suitable for various analytic purposes. Thus SOC comprises:

- 9 Major Groups, subdivided into

- 22 Sub-major groups, subdivided into

- 77 Minor Groups, subdivided into

- 371 Unit Groups created from

- 3,800 CODOT occupational titles.

Most of the work ln developing SOC went into the definition of the Unit Groups, with which users are mainly concerned. The aim was to adapt the structure of the 350 Occupational Coding Groups used in the C080 to meet the SOC criteria.

Over half (56.3%) of the Occupational Coding Groups match with the SOC Unit Groups on a one to one basis, and a further 4.9% can be exactly reconstructed by aggregating two or more SOC Unit Groups. Of the others which cannot be exactly matched, a significant number differ only slightly from the SOC Unit Groups thus providing a reasonably good overall fit. Much of the remaining discontinuity affects the residual 'nec' groups in C080. See also 1991 Census definitions p.37-39 and 1991 Census Appendix 8 and 9.

Pensionable Age


The minimum age at which a person may receive a national insurance retirement pension ie. 60 years for a woman, 65 years for a man.

Population Bases


Combinations of the answers given at Question 6 (wherabouts on Census night) and Question 7 (usual address) form the building bricks for the various population bases as follows:


Population Group

Usual Address



Present residents

This address

This address


Visitors from within GB

Elsewhere in GB

This address


Visitors from outside GB

Outside GB

This address


Absent residents absent within GB

This address

Elsewhere in GB


Absent residents absent outside GB

This address

Outside GB

Categories (d) and (e) are not enumerated in communal establishments. Persons in category (d) should also be in category (b) on the form completed where they are present on Census night.

Population Present


Or persons present, is a count of all the persons recorded as spending Census night in an area regardless of whether this was where they usually lived. See also De Facto.

Qualified Manpower


Question 19 on the Census form requested, for all persons aged 18 and over, details of degrees and professional and vocational qualifications obtained. The question was in the same form as the one included in the 1981 Census. The qualification code indicates the type and level of the qualification eg degree, diploma etc, and the subject code indicates the subject, or combination of subjects, in which the qualification was obtained. The awarding institution and the year of the award are not coded, but the information is used to improve the accuracy of the coding.

Relationship in Household


Used in the analysis of the composition of households. The aim of the approach is to classify households taking account of the inter-relationships between household members. Each members relationship to the head of household is classified. The head of household or a joint head, or other member of the household is entered as person one on the Census household form and the relationship to that person is answered for all other persons on the form.

The question is very similar to the one asked in 1981 but, additionally, attempts to identify by means of a stated category on the form rather than by the coding of write-in answers.

Step and adopted relationships, when specified as such on the form, are not distinguished from blood relationships.

The list of relationship codes differs from that followed in 1981 only in that cohabitant (code 2) replaces the former de facto spouse (derived from write-in answers) and that additional codes are introduced for child of cohabitant and cohabitant of son/daughter.

Social Class


Since the 1911 Census it has been customary to arrange the large number of groups in the classification of occupations into a smaller number of summary categories called Social Classes. In the 1991 Census persons with a paid job are assigned to a Social Class by reference to their occupation in the week preceding the Census, or where there was no paid job, on the basis of the most recent paid job held within the previous ten years.

Members of the armed forces and those with inadequately described occupations are not allocated a social class; persons on a government employment or training scheme are similarly not allocated a social class.

After a consultation exercise in 1989 OPCS decided to retain the name 'social class' but to expand it to Social Class based on occupation in order to make its basis more explicit.

The proposal to change the name of Social Class II from Intermediate Occupations to Managerial and Technical Occupations was welcomed and has been implemented.

Notwithstanding these minor changes to the nomenclature of the classification, the occupation groups included in each of the social class categories, are, as in 1981, selected in such a way as to bring together as far as possible people with similar levels of occupational skill. In general, for the 1991 Census, each SOC Unit Group is assigned as a whole to one or other social class and no account is taken of differences between individuals in the same group, such as differences of education or levels of remuneration. However, for persons having the employment status of 'foreman' or 'manager' the following additional rules apply:

- each occupation is given a basic social class

- persons of 'foreman' status whose basic social class is IV or V are allocated to Social Class III; and

- persons of 'manager' status are allocated to Social Class II with certain exceptions.

Socio-economic Group


Classification by socio-economic group (SEG) was introduced in the 1951 Census and extensively amended in 1961. This non hierarchical classification aims to bring together people with jobs of similar social and economic status. The allocation of occupied persons to an SEG is determined by considering their employment status and occupation.

It is not practical to obtain from a census the degree of responsibility exercised by employers and managers. An indirect distinction between greater and lesser responsibility is provided by classifying employers and managers by the size of the establishment in which they work. SEGs 1.1 and 1.2 comprise respectively, employers and managers in enterprises employing 25 or more persons, while SEGs 2.1 and 2.2 comprise those in enterprises employing fewer than 25 persons. Civil servants, local authority officials and ships' officers are conventionally regarded as working in large establishments.

Student's Term-Time Address


A student's usual address is taken for annual estimates purposes as the term-time address, but in the 1981 Census this was considered to be the student's home address. Statistics derived from the 1981 Census were therefore not directly comparable with the Registrar General's annual estimates. The date of the 1991 Census fell in term time for some educational establishments but in vacation time in others. The Census included a new question on term time address of students and school children.

Subject Group


The major subject(s) of each qualification that a person holds is coded using a standard subject classification, consisting of 10 subject groups and 108 primary subjects.

Tenure Dwellings


The tenure of a dwelling is chosen with reference to the tenure(s) of the constituent household space(s). For a dwelling of one household space, the tenure of the dwelling will be the same as that of the household space. For a multi-household space dwelling the tenure is chosen according to a priority order. The highest ranked tenure among the household spaces becomes the tenure for the dwelling.

Tenure of Accommodation Household Spaces


The tenure of the household's accommodation was obtained from the answer to Question H3.

The division of owner-occupiers into 'buying through mortgage or loan' and 'owning outright' represents a slight difference from the categories adopted in England and Wales in 1981 when owner-occupation was classified as either freehold or leasehold, irrespective of whether the property was being purchased by mortgage or owned outright.

In England and Wales the renting categories are the same as 1981 except that the category 'renting from a New Town Development Corporation or from a Housing Action Trust' is separately identified on the 1991 Census form to reflect the increase in this sector of the housing market.



The journey to work question asked about the longest part, by distance, of the person's normal daily journey to work. The categories listed are the same as in 1981 except that the former category 'car pool /sharing driving' is no longer separated from 'driving a car or van' or 'passenger in a car or van'. Where more than one box was ticked the lowest number was coded.

Type of Move


A migrant within a defined area is one whose former usual address and usual address at Census are within the same defined area.

A migrant to a defined area is a migrant whose usual address at Census was inside the defined area but whose former usual address was outside that area.

A migrant from overseas to a defined area is a migrant whose address at Census was inside the defined area but whose former usual address was outside Great Britain. (This definition carries no implication with regard to birthplace or ethnic group of the migrant.)

A migrant from a defined area is a migrant whose former usual address was inside the defined area but whose usual address at Census was outside the area but within Great Britain.

Migrants resident in a defined area is the sum of migrants within the area and migrants into the area, including those migrants resident in the area with origin not stated. Migrants from/to contiguous areas are defined as the sum of all migrants from/to areas which have a shared boundary with the defined area.

Usual Address


Indicates where a person usually lives. For most people the answer to the question on usual address is straightforward. For some, however, it is not so particularly when a person lives at more than one address throughout the year.

Question 7 (Usual address) on the H and I forms included the instruction that, for students or (school)children away from home during term-time, their home address should be taken as their usual address.

The governors of prisons were advised that if a prisoner had served six months or more of a sentence (though not necessarily at the same establishment) immediately prior to Census night, the usual address should be taken to be the address of the prison. If less than six months had been served, the usual address before admission should be given. A similar procedure was followed for children in community homes.

Usually Resident Population


(Topped up present/absent: 1991 base) is a count of all persons recorded as resident in households in an area, even if they were present elsewhere on Census night, plus residents in communal establishments who were present in the establishment on Census night. This population is 'topped up' with persons from enumerated wholly absent households and imputed wholly absent households. See also De Jure and 1991 Census definitions p.7-8.



Those persons present at this address on Census night whose usual address was not this address.



Question 6 on the Census form. Used in conjunction with Question 7, Usual address, to define population bases. If 'Elsewhere' was ticked and an address elsewhere in Great Britain was given, then the input is the postcode of that address; if an address outside GB was given, then the input is the country of usual residence (using the same codes as the country of birth classification). Where there was no answer to the question on usual address, or where the answer was 'none' or 'no fixed address' the imputation procedure provides a code of either 'this address' or 'elsewhere, not stated'. See also Population Bases.