FILE STRUCTURE AND USE
Nature of the levels
Each of the CURFs contain the following record levels:
- Household level - contains information about State or Territory and area (Capital City/Balance of State) of residence, type of dwelling, tenure type, landlord type, household type and composition, household income and number of income earners, disability, household items (such as televisions and vehicles), household use of Internet technology, and some information relating to the household reference person;
- Family level - contains information about family composition, child care, disability, and some information relating to the family reference person;
- Person level - contains information about each selected person, the family and household to which they belong, such as: sex, age, marital status, relationship in household, country of birth, year of arrival in Australia, family type, income unit type, labour force details, occupation and industry, education status, education qualifications and educational institution attending, income by detailed source of income, child care, carer and disability information, use of Internet technology, time use. Person records only exist for persons aged 15 and over;
- Day level - contains information about the nature of the day, the quarter of collection and the day of the week the diary information related to;
- Episode level - contains information about each segment of time throughout the day, such as: who was present, length of episode, start and stop time of episode, who activity was done for, health information about person(s) present, spatial and physical location of episode, mode of transport used, and type of communication/information technology used during the episode as recorded in the TUS diary; and
- Activity level - contains information about what was happening during each episode such as the nature and purpose of activity as recorded in the TUS diary, and an activity concordance to 1992 Time Use Survey. It also provides information about whether the activity was a primary or secondary activity (where the person stated that they were doing two things at the same time, such as cooking dinner and watching television).
Table 8.5 shows the number of records on each level.
Table 8.5 Record counts
TUS Expanded CURF
TUS Basic CURF
|Household level |
|Family level |
|Person level |
|Day level |
|Episode level |
|Activity level |
There are seven identifiers on the expanded and basic CURFs.
Every household has a unique random identifier (ABSHID). This identifier appears on the household level, and is repeated on the family, person, day, episode and activity levels for each record relating to that household.
Each family within a household is numbered sequentially commencing at 1. Non-family members, single person households and persons in group households have a sequential "family number" commencing at 50. Family number (ABSFID) appears on the family level and is repeated on the person, day, episode and activity levels for each record relating to that family. The combination of household and family number uniquely identifies a family.
A family has one or more income units and each income unit within the family is numbered sequentially. Income unit number (ABSIID) appears on the person, day, episode and activity levels. The combination of household, family, and income unit number uniquely identifies an income unit.
An income unit has one or more persons and each person within the income unit is numbered sequentially. Person number (ABSPID) appears on the person level and is repeated on the day, episode and activity levels. The combination of household, family, income unit and person number uniquely identifies a person.
A person has records for up to two days and each day within a person record is numbered sequentially. Day number (ABSDID) appears on the day level and is repeated on the episode and activity levels. The combination of household, family, income unit, person and day number uniquely identifies a day.
A day has one or more episode records and each episode within a day record is numbered sequentially. Episode number (ABSEID) appears on the episode level and is repeated on the activity level. The combination of household, family, income unit, person, day and episode number uniquely identifies an episode.
An episode has one or more activities and each activity within an episode record is numbered sequentially. Activity number (ABSAID) appears on the activity level. The combination of household, family, income unit, person, day, episode and activity number uniquely identifies an activity.
At higher levels, level identifiers for lower levels are set to zero.
Children aged under 15 years
Children aged under 15 years do not have their own person level record on the file. Information on the number and ages of such children was collected and is included on the household and family level files.
Persons aged 15 years and over
In some cases persons aged 15 years and over included in family and household level variables may not have individual person, day, episode or activity records on the CURF files. These individuals either had no useable diary information or interview details and were dropped based on the rules detailed in the section 'Number of records on the final file' (see Chapter 3 'Survey Methodology').
Use of weights
The CURFs contain records which can be adjusted (weighted) to infer results for the total in-scope population in Australia. As the survey was conducted on a sample of private dwellings in Australia, it is important to take account of the method of sample selection when deriving estimates from the CURFs. This is particularly important as a person's chance of selection in the survey varied depending on the State or Territory in which the person lived, as well as the days of the week they were asked to respond for. If the chance of selection is not accounted for, by use of appropriate weights, the results will be biased. For information about the derivation of the weights for the 2006 TUS see Chapter 3 'Survey Methodology' in this User Guide.
Each household, family, person, day, episode and activity record contains a weight. This weight indicates how many population units are represented by the sample unit. Weights for each family record are the same as the weights for the household record. Likewise, weights for the episode and activity records are the same as the weights for the person-day record. Care needs to be taken to ensure the appropriate weight is selected when estimating for the desired Australian population (see Appendix 2 for weights at each level).
In addition, replicate weights have been included on the CURFs which can be used to calculate sampling error. Sampling error arises because the estimates are based on a sample of units and so will differ from estimates that would have been produced if all units in the population had been included in the survey. Each record on the CURFs contain 60 'replicate weights' in addition to the associated 'main weight'. Information on the use of these replicate weights is provided in the section 'Reliability of the estimates' below.
Weights are calibrated against population benchmarks to ensure that estimates conform to an independently estimated distribution of the population by certain characteristics, rather than to the distributions within the sample itself. Separate benchmarks are used for each enumeration period, and include households and persons residing in occupied private dwellings only. The benchmarks sum to an averaged "yearly" private dwelling population, and therefore do not, and are not intended to, match estimates of the total Australian resident population published by the ABS. For information about the benchmarks used in the calibration of the final weights please see Chapter 3 'Survey Methodology' in this User Guide.
If estimates of population sub-groups are to be derived from the CURFs, it is essential that they are calculated using the appropriate weights of records in each category and not just by counting the number of records in each category. If weights for each category were to be ignored when analysing the data to draw inferences about the population of interest, then no account would be taken of the chance of selection or of different response rates across population groups.
It should be noted that as a result of some of the changes made to protect confidentiality on the CURFs, estimates of benchmarked items produced from the CURFs may not equal the benchmarked values. Further information about this difference in estimates is presented in the section 'About the Microdata' at the start of this chapter.
Reconciliation of the data
It is not possible to reconcile exactly the data produced from the CURFs with published data. This is a result of the steps taken to preserve confidentiality. These steps are outlined in the section 'About the Microdata' at the start of this chapter.