1 This publication contains preliminary estimates of the civilian labour force derived from the Labour Force Survey component of the monthly population survey. Estimates for the current month are preliminary and subject to revision. Revised estimates for the current month and more detailed estimates will be published in Labour Force, Australia (Cat. no. 6203.0).
CONCEPTS, SOURCES AND METHODS
2 The conceptual framework used in Australia’s Labour Force Survey aligns closely with the standards and guidelines set out in Resolutions of the International Conference of Labour Statisticians. Descriptions of the underlying concepts and structure of Australia's labour force statistics, and the sources and methods used in compiling the estimates, are presented in Labour Statistics: Concepts, Sources and Methods (Cat. no. 6102.0) which is also available on the ABS website www.abs.gov.au (Statistics-Statistical Concepts Library).
MONTHLY POPULATION SURVEY
3 The population survey is based on a multi-stage area sample of private dwellings (currently about 30,000 houses, flats, etc.) and a list sample of non-private dwellings (hotels, motels, etc.), and covers about 0.5% of the population of Australia. The information is obtained from the occupants of selected dwellings by specially trained interviewers. The information obtained relates to the week before the interview (i.e. the reference week).
4 The interviews are generally conducted during the two weeks beginning on the Monday between the 6th and 12th of each month. Each year, to deal with operational difficulties involved with collecting and processing the Labour Force Survey around the Christmas and New Year holiday period, interviews for December start four weeks after November interviews start, and January interviews start five weeks after December interviews start. Occasionally, circumstances that present significant operational difficulties for survey collection can result in a change to the normal pattern for the start of interviewing.
5 Estimates from the Labour Force Survey are published first in this publication 31 days after the commencement of interviews for that month, with the exception of estimates for each December which are published 38 days after the commencement of interviews.
6 The ABS has introduced the use of telephone interviewing into the Labour Force Survey. Households selected for the Labour Force Survey are interviewed each month for 8 months, with one eighth of the sample being replaced each month. The first interview is conducted face-to-face. Subsequent interviews are conducted by telephone (if acceptable to the respondent). Telephone interviewing was phased in for each new sample group from August 1996 to February 1997.
7 During the period of implementation, the new method produced different estimates than would have been obtained under the old methodology. The effect peaked in November 1996, when it is estimated that the published estimate of total employment was about 36,000 to 48,000 lower than would have been measured under the old methodology. The effect dissipated over the final months of implementation and was no longer discernible from February 1997. Therefore, the estimates for February 1997 and onwards are directly comparable to estimates for periods prior to August 1996.
SCOPE OF SURVEY
8 The Labour Force Survey includes all persons aged 15 and over except members of the permanent defence forces, certain diplomatic personnel of overseas governments customarily excluded from census and estimated population counts, overseas residents in Australia, and members of non-Australian defence forces (and their dependants) stationed in Australia.
9 In the Labour Force Survey, coverage rules are applied which aim to ensure that each person is associated with only one dwelling, and hence has only one chance of selection. The coverage rules are necessarily a balance between theoretical and operational considerations. Nevertheless, the chance of a person being enumerated at two separate dwellings in the survey is considered to be negligible.
10 Labour Force Survey estimates are calculated in such a way as to add up to independent estimates of the civilian population aged 15 and over (population benchmarks). From February 1999, labour force estimates have been compiled using benchmarks based on the results of the 1996 Census of Population and Housing. Small revisions were made to many of the historical estimates from January 1995 to January 1999.
REVISION OF SERIES
11 From April 1986, the definition of employed persons was changed to include persons who worked without pay between 1 and 14 hours per week in a family business or on a farm (i.e. contributing family workers). For further information, see paragraphs 36 and 37 of the Explanatory Notes to the February 1987 issue of Labour Force, Australia (Cat. no. 6203.0).
12 From April 2001 the Labour Force Survey has been conducted using a redesigned questionnaire containing additional data items and some minor definitional changes. Core labour force series were revised for the period April 1986 to March 2001 to ensure continuity. For further details, see Information Paper: Implementing the Redesigned Labour Force Survey Questionnaire (Cat. no. 6295.0) and Information Paper: Questionnaires Used in the Labour Force Survey (Cat. no. 6232.0).
SURVEY SAMPLE REDESIGN
13 The Labour Force Survey sample was last reselected using information collected in the 1996 Census of Population and Housing.
14 The bulk of the new sample was phased in over the period September 1997 to April 1998, with one eighth of this portion of the sample being introduced every month. The remainder of the sample (about 15% of the total), which covers less settled areas of Australia and non-private dwellings was rotated in full for New South Wales, Victoria, Tasmania, Northern Territory and Australian Capital Territory in September 1997, and for Queensland, South Australia and Western Australia in October 1997. Such a pattern of implementation means that any changes to labour force estimates due to differences between the two samples, or any other influences, were spread over the eight months.
15 For further details, see Information Paper: Labour Force Survey Sample Design (Cat. no. 6269.0).
RELIABILITY OF ESTIMATES
16 Two types of error are possible in an estimate based on a sample survey: sampling error and non-sampling error.
Sampling error occurs because a sample, rather than the entire population, is surveyed. One measure of the likely difference resulting from not including all dwellings in the survey is given by the standard error. There are about two chances in three that a sample estimate will differ by less than one standard error from the figure that would have been obtained if all dwellings had been included in the survey, and about nineteen chances in twenty that the difference will be less than two standard errors. Standard errors of estimates for the latest month and of estimates of movements since the previous month are shown on pages 31 and 32. Standard errors of other estimates and other movements may be determined by using information in the Technical Notes in Labour Force, Australia (Cat. no. 6203.0).
Non sampling error arises from inaccuracies in collecting, recording and processing the data. Every effort is made to minimise reporting error by the careful design of questionnaires, intensive training and supervision of interviewers, and efficient data processing procedures.
SEASONAL ADJUSTMENT AND TREND ESTIMATION
17 Seasonally adjusted series are published in Tables 2, 5 and 12 to 17. Seasonal factors are reviewed annually to take account of each additional year’s original data. Information about the last annual review of seasonal factors was published in a feature article in the February 2001 issue of Labour Force, Australia (Cat no. 6203.0). An additional review was conducted following the revision of series associated with the introduction of the redesigned questionnaire in April 2001 (see paragraph 12). The results of this additional review were used to compile the seasonally adjusted and trend estimates in this publication.
18 Seasonal adjustment is a means of removing the estimated effects of normal seasonal variation from the series so that the effects of other influences on the series can be more clearly recognised. Seasonal adjustment does not aim to remove the irregular or non-seasonal influences which may be present in any particular month. This means that month-to-month movements of the seasonally adjusted estimates may not be reliable indicators of trend behaviour. For example, irregular factors unrelated to the trend account for more than half the seasonally adjusted movement with the following frequency:
Employment: 6 in 10 monthly movements
Unemployment: 8 in 10 monthly movements
Unemployment rate: 7 in 10 monthly movements
Participation rate: 9 in 10 monthly movements.
19 The smoothing of seasonally adjusted series reduces the impact of the irregular component of the seasonally adjusted series, and creates trend estimates. These trend estimates are derived by applying a 13-term Henderson-weighted moving average to all months except the last six. The last six monthly trend estimates are obtained by applying surrogates of the Henderson average to the seasonally adjusted series. Trend series are used to analyse the underlying behaviour of the series over time. These are published in tables 3, 6 and 12 to 19.
20 While this smoothing technique enables estimates to be produced for the latest month, it does result in revisions to the most recent months as additional observations become available. Generally, subsequent revisions become smaller, and after three months have a negligible impact on the series. There will also be revisions as a result of the annual review of seasonal factors.
21 Trend estimates are published for the Northern Territory in table 18 and for the Australian Capital Territory in table 19. Unadjusted series for the two Territories have shown, historically, a high degree of variability, which can lead to considerable revisions to the seasonally adjusted estimates after each annual seasonal factor re-analysis. Seasonally adjusted estimates are not currently published for the two Territories. The most recent six months trend estimates are subject to revision. For the three most recent months, the revision may be relatively large. Inferences about trends drawn from smoothed seasonally adjusted (trend) estimates for months earlier than the latest three months are unlikely to be affected by month to month revisions. They may be affected by revision resulting from the annual re-analysis of seasonal factors.
22 For further information, see A Guide to Interpreting Time Series-Monitoring ‘Trends’: an Overview (Cat. no. 1348.0) or contact the Assistant Director, Time Series Analysis on (02) 6252 6345.
23 Users may also wish to refer to Labour Force, Australia (Cat. no. 6203.0). This publication contains a detailed list of related publications which are available from ABS Bookshops.
24 Current publications produced by the ABS are listed in the Catalogue of Publications and Products (Cat. no. 1101.0). The ABS also issues, on Tuesdays and Fridays, a Release Advice (Cat. no. 1105.0) which lists publications to be released in the next few days. The Catalogue and Release Advice are available from any ABS office.
DATA AVAILABLE ON REQUEST
25 As well as the statistics included in this and related publications, the ABS may have other relevant data available. Inquiries should be made to Mark Webb on 02 6252 6525 or to any ABS office.
EFFECTS OF ROUNDING
26 Estimates have been rounded and discrepancies may occur between sums of the component items and totals.
27 Estimates of movement shown in this publication are obtained by taking the difference of unrounded estimates. The movement estimate is then rounded to one decimal place. Therefore where a discrepancy occurs between the reported movement and the difference of the rounded estimates, the reported movement will be more accurate.
SYMBOLS AND OTHER USAGES
|subject to sampling variability too high for most practical uses.|
See the Technical Notes in Cat. no. 6203.0 for more details