USING THE CURF MICRODATA
ABOUT THE MICRODATA
The LFS and Labour Mobility microdata are released under the Census and Statistics Act 1905, which has provision for the release of microdata in the form of unit records where the information is not likely to enable the identification of a particular person or organisation. Accordingly, there are no names or addresses of survey respondents on the CURF and other steps have been taken to protect the confidentiality of respondents. These include removing some data items from the CURF, reducing the level of detail shown on the CURF for some other items and swapping some characteristics between records.
Steps to confidentialise the data sets made available on the CURF are taken in such a way as to ensure the integrity of the data sets and optimise their content, while maintaining the confidentiality of respondents. Intending purchasers should ensure that the data they require, at the level of detail they require, are available on the CURF they are intending to use; data obtained in the survey but not contained in the CURF may be available in tabulated form on request. The full list of survey data items included on the CURF is provided in Appendix 2, Data Item List.
The CURF contains 63,831 confidentialised respondent records. Each person record has a unique person identifier (ABSPID). Subject to the limitations of sample size and the data classifications used, it is possible to manipulate the microdata, produce tabulations and undertake statistical analyses to individual specifications.
The CD-ROM version of the CURF is available in SAS, SPSS and STATA formats.
Five types of files relating to LFS and Labour Mobility 2006 microdata are provided on the CURF:
- Data and metadata - an ASCII data file holding 63,831 records, and metadata files that document the data file and every data item on that file. The metadata are provided in a plain text file, for reading
- SAS user files - including a SAS version of the data set, and the SAS programs that generated the SAS-formatted version
- SPSS user files - including an SPSS version of the data set
- STATA user files - including a STATA version of the data set; and
- Information files - including several in Adobe Acrobat format.
USE OF WEIGHTS
As the survey was conducted on a sample of households in Australia, it is important to take account of the method of sample selection when deriving estimates from the CURF. This is particularly important as a person's chance of selection in the survey varied depending on the state or territory in which they lived.
Each person record contains two weights, an LFS weight called LFSWTD and a weight to be used for Labour Mobility called FINPRSWT. These weights indicate how many people are represented by that person. There are two weights because the scope of the LFS is different to the scope of the Labour Mobility survey. For data items that are only applicable to Labour Mobility (refer to Appendix 2, Data Item List), it is important to use the Labour Mobility weight, FINPRSWT. Users should take care to ensure the appropriate weight is used for analysis.
The LFS weight is available on all records on the CURF. The Labour Mobility weight, FINPRSWT, appears on approximately 35,637 records. The estimates in the Labour Mobility publication are based on a subset of these records, that is employees in main job. Therefore when using FINPRSWT, in order to match published Labour Mobility estimates, the filter POPSUP = 1 must be used.
Where estimates are derived from the CURF, it is essential that they are calculated by adding the weights of persons in each category and not just by counting the number in each category. If each person's 'weight' were to be ignored, then no account would be taken of a person's chance of selection or of different response rates across population groups, and the resulting estimates could be seriously biased.
The application of weights will ensure that the subsequent estimates conform to an independently estimated distribution of the population by age and sex, rather than to the age and sex distribution within the sample itself.
For further information see the Explanatory Notes in the publications Labour Force, Australia, February 2006 (cat. no. 6202.0) and Labour Mobility, Australia, February 2006 (cat. no. 6209.0) on the CURF CD-ROM as Acrobat files 62020_FEB 2006.PDF and 6209_FEB 2006.PDF.
RECONCILIATION OF CURF WITH UNCONFIDENTIALISED DATA
Steps to confidentialise the data made available on the CURF are taken in such a way as to maximise the content of the file while maintaining the confidentiality of respondents. The steps taken to preserve confidentiality may include:
As a result, it may not be possible to exactly reconcile all statistics produced from the CURF with published statistics.
- reducing the level of detail for some items (e.g. geographic and demographic)
- ranging or collapsing the values of some variables; and
- modifying some records identified as high risk.
For further information about using the microdata contained in the CURF, contact the Labour Market Statistics Section on (02) 6252 7206.