2901.0 - Census Dictionary, 2001  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 24/04/2001   
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Undercounting and/or underenumeration
Unit record file
Unoccupied private dwelling
Unpaid helpers
Unrelated child (under 15)
Unrelated individual living in a family household
Urban Centre/Locality
Usual address
Usual residence

Undercounting and/or underenumeration

Census collectors direct extensive efforts toward locating dwellings and households within districts, however locating them all is sometimes not possible. Some dwellings may not be identified. For example, in commercial areas flats above or behind shops may be difficult to find. Also, particularly where contact is not made at delivery, flats behind or attached to private dwellings may not be included in the Census. Analysis of the undercount in previous censuses has shown that people away from their usual residence on Census Night (for example, travelling, camping, staying in a non-private dwelling, or visiting friends) are more likely to be missed than people at home on Census Night.

Even when a household is found, undercount is possible if not all members of the household are included on the form (for example, if there are more than six people in the household and no extra forms are obtained) or if the household, or a member of the household, refuses to cooperate and complete a census form.

A measure of the extent of underenumeration is obtained from the Post Enumeration Survey (PES). The official population estimates produced by the ABS take into account the results of the PES. However, the census counts are not adjusted. See also Post Enumeration Survey (PES).


See Labour Force Status/Status in Employment (LFSP).

Unit record file

The Unit Record File (URF) is a sequence of records held on computer files. It holds coded data for all the person, family and dwelling characteristics in each Collection District (CD) as collected in the Census. It is the original source of all census products. It excludes records for persons listed as temporarily absent, as their details will have been recorded at their place of enumeration on Census Night.

Census data are stored in a hierarchy of records for each dwelling. Each dwelling may contain a number of family records. Each of these, in turn, may contain a number of person records. When using household/family data it is necessary to recognise these three levels and understand the concepts at each level.

The three levels are indicated by the last character in the mnemonic for each variable. Dwelling level variables are indicated by D, family level by F, and person level by P.

The URF is held under strict security and is only accessible by certain officers of the ABS. See also Estimated Resident Population (ERP), Data processing, Mnemonic.

Unoccupied private dwelling

See Dwelling.

Unpaid helpers

See Contributing family worker, Labour Force Status/Status in Employment (LFSP).

Unrelated child (under 15)

See Child under 15.

Unrelated individual living in a family household

A person who lives in a family household, but who is not related to any person in any of the families in the household, but who shares meals with a family. A boarder fits into this category. See also Relationship in Household (RLHP).

Urban Centre/Locality

An Urban Centre is generally defined as a population cluster of 1,000 or more people. A Locality is generally defined as a population cluster of between 200 and 999 people. People living in Urban Centres are classified as urban for statistical purposes while those in Localities are classified as rural (i.e. non-urban). Each Urban Centre and/or Locality (UC/L) is bounded (i.e. a boundary for it is clearly defined) and composed of one or more whole Collection Districts (CDs). UC/Ls are defined for each Census and are current for the date of the Census. The criteria for bounding UC/Ls are based on the Linge methodology.

For more information and a list of the UC/Ls for 2001, refer to Statistical Geography  Volume 3: Australian Standard Geographical Classification (ASGC) Urban Centres/Localities (Cat. no. 2909.0). See also Section of State.

Usual address

Usual address information is used to code usual residence. See also Usual residence.

Usual residence

Usual residence data provide information on the usually resident population of an area, and on the internal migration patterns at the State and regional levels. The 2001 Census has three questions on usual residence that ask where the person usually lives on Census Night, and where the person usually lived one year ago, and five years ago.

In 1996, 'usual residence' was defined in the Question 7 notes as:

  • that address at which the person has lived or intends to live for a total of 6 months or more in 1996;
  • for people who now have no usual address, write no usual address; and
  • for boarders at boarding school or college, give the address of the school or college.

For 2001 an additional note was included, 'For persons who usually live in another country and who are visiting Australia for less than one year, mark Other country'.

The information acquired from the answers to the usual residence questions is recorded in the variable Postal Area of Usual Address Census Night (POCUCP), and in the usual residence indicator variables:

  • Usual Address Indicator Census Night (UAICP)
  • Usual Address One Year Ago Indicator (UAI1P)
  • Usual Address Five Years Ago Indicator (UAI5P)

Use of usual residence indicators, in conjunction with the other variables relating to usual residence, make it possible to identify the pattern of net movement of people between three dates, i.e. Census Night, one year ago and five years ago.

For the 2001 Census there have been some changes to editing and processing procedures for the variables UAI1P and UAI5P. These changes will address minor data quality issues identified from the 1996 Census, which affected less than one percent of the population. Further information is available from the Census Fact Sheet on Usual Residence, or by contacting Information Consultancy.

For the 2001 Census, usual residence data are available at Collection District (CD) level. However, where the respondent has provided insufficient address information, the SLA will be imputed as in the past, but the CD will not be imputed.

The following usual residence variables are available:

  • CD of Usual Residence Census Night (CDUCP)
  • SLA of Usual Residence Census Night (SLAUCP)
  • SLA of Usual Residence One Year Ago (SLAU1P)
  • SLA of Usual Residence Five Years Ago (SLAU5P)
  • State of Usual Residence Census Night (STEUCP)
  • State of Usual Residence One Year Ago (STEU1P)
  • State of Usual Residence Five Years Ago (STEU5P).

(State is necessary to delimit Statistical Local Area (SLA) because the SLA code is not unique across Australia.)

Most respondents enumerated at a place other than their usual residence provide sufficient information for their usual residence to be coded to a CD. However, in some cases a code of 'State undefined' or 'Capital City undefined' must be allocated and in some cases no response is given.

If there is inadequate information to allocate a code for usual residence, the CD of a parent (if the person is under 15) or spouse (if the person is 15 or older) is allocated. This is presuming a parent or spouse is recorded on the census form with their usual residence details completed.

A number of people were enumerated on board vessels in or between Australian ports (or on long-distance trains, buses or aircraft) on Census Night. If they give an address in Australia as their usual residence, they are coded to the CD containing that address. A small number indicated that they were usually resident at the address at which they were enumerated. They were allocated a separate usual residence code describing them as Migratory.

If no adequate response is given for usual residence for persons enumerated in Non-Private Dwellings (e.g. hotels, motels, hospitals) the SLA is imputed using population distribution patterns from the 1996 Census. Similar imputation is done for visitors in private dwellings.

If no code can be allocated for SLA of usual residence one or five years ago, a code of Not Stated is given. The only exceptions to this are where the person is 16 or younger (for usual residence one year ago) or 20 years or younger (for usual residence five years ago) and there is a parent present with the appropriate SLA coded. The SLA code of the parent is then allocated to the person.

Family variables are only derived for people counted at their usual residence. Temporarily absent persons are used to classify types of relationships and families existing in a household, but they are not used in the derivation of any other census characteristics or in other census output. If all members of a family are absent from their usual residence, no family records are created for them. Family and household structures are based on persons usually resident. If all members of a family or household are temporarily absent, the family or household is not counted.

Usual Residence data are used by the ABS in calculations of the Estimated Resident Population. See also Census counts, Migratory collection district, Place of usual residence, Temporarily absent, Visitors to a household.

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