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25.4 Data published from the first series are available on the following bases: original; seasonally adjusted; and trend (see Chapter 16 for further explanation of original, seasonally adjusted and trend estimates). Data from the second series, job vacancy rates, are available on an original basis only.
25.5 Data from both series can be cross classified by: State and Territory; sector; and industry (ANZSIC 1 digit).
25.6 Estimates are compiled according to the concepts and definitions outlined in Chapter 4 (employees) and Chapter 10 (job vacancies).
25.7 The scope of the survey is restricted to employing businesses (MUSs). In addition, the standard scope exclusions for ABS labour-related business surveys (outlined in Chapter 23) apply to this survey.
25.8 The standard scope exclusions for ABS labour-related business surveys (outlined in Chapter 23) apply to this survey.
25.9 Details of the total number of employee job vacancies available for immediate filling on the survey reference date, and number of employee jobs for which payments were made during the survey reference period, are obtained on a quarterly basis from selected businesses. A telephone interview collection methodology is used.
25.10 The survey reference period for the number of employee jobs is the last pay period ending on or before the third Friday in the middle month of the quarter. The survey reference date for job vacancies is the third Friday in the middle month of the quarter.
25.11 Follow-up procedures are in place to obtain information from respondents who are unable to provide data at the time of the initial interview. Response rates for the survey averaged 98% in the 1998-99 financial year.
25.12 The selection unit for the survey is Management Unit/State (MUS). The collection and reporting units used in the survey usually correspond to the selection unit. However, where the MUS unit is unable to provide information required for the survey, it may be split into a number of 'reporting units'. For further information on statistical units used in ABS business surveys refer to Chapter 23.
25.13 A probability sample of MUS units (employing businesses) is drawn from the ABS Business Register using the process outlined in Chapter 23. Variables used to stratify the survey frame are:
25.14 Strata on the survey frame that are completely enumerated include those containing MUSs with benchmark employment greater than a set cutoff (this cutoff will vary for different States/Territories) and strata with a very small number of MUSs. Strata which are completely enumerated because they contain a low number of MUSs may become sampled strata if the number of MUSs in those strata increases sufficiently.
25.15 In addition to constraints outlined in Chapter 23, sample selection is constrained by ensuring that there is minimum overlap with other labour-related business surveys.
SAMPLE SIZE AND ALLOCATION
25.16 Approximately 4,500 MUSs are selected in the sample to yield a live sample of approximately 3,800 MUSs.
25.17 The sample is allocated optimally across the strata using a technique designed to minimise the variance of job vacancies estimates at both the national and State/Territory level.
25.18 The sample is updated each quarter to reflect changes in the ABS Business Register. Approximately 8% of the sample selected from the non-completely enumerated strata is replaced each quarter. This process is called sample rotation (see Chapter 23 for further explanation).
25.19 Sample rotation is implemented for the majority of strata, but is not implemented where the population of a stratum is so small that units rotating out of the sample would be rotated back in after only a short interval.
25.20 Ratio estimation is used in all strata, except in cases where there is a large proportion of units with zero benchmark employment, in which case number-raised estimation is used.
25.21 In the sampled strata the Live Respondent Mean method of imputation is used for units not responding. In the completely enumerated strata an imputed growth rate is applied to the most recently reported data for the unit, provided that data have been reported in either of the two previous quarters. Otherwise, the Live Respondent Mean is used, adjusted for the ratio of the unit's benchmark employment on the frame to the Live Respondent Mean for employment in the strata.
25.22 Survey outliers are treated using the 'surprise outlier' technique.
25.23 New Business Provisions were introduced in November 1999. Adjustments are made to survey estimates each quarter to allow for births and deaths of businesses that have occurred up to the end of the survey reference period but which are not reflected on the survey frame.
25.24 For further information on estimation methods used in ABS Business Surveys, refer to Chapter 23.
TIME SERIES ESTIMATES
25.25 Both seasonally adjusted and trend estimates are produced for the job vacancies series. Data from the job vacancy rates series are available on an original basis only.
25.26 The series have been seasonally adjusted from February 1984, and these historical series can be made available on request. The seasonal factors are reviewed annually to take account of each additional year's original data. The review takes place in time for the results to be incorporated in each November quarter issue of Job Vacancies, Australia (Cat. no. 6354.0).
25.27 Trend estimates were introduced in August 1993, and are revised each quarter.
RELIABILITY OF THE ESTIMATES
25.28 Estimates from the survey are subject to both sampling and non-sampling error. The relative standard errors of survey estimates are published in Job Vacancies, Australia (Cat. no. 6354.0).
25.29 The 'jack-knife' approach is used to calculate estimates of variance for this survey. For further information on the jack-knife technique for calculating variance, or on sampling and non-sampling error, refer to Chapter 16.
DATA COMPARABILITY OVER TIME
25.30 In order to provide a high degree of consistency and comparability over time, changes to survey methods, survey concepts, data item definitions, frequency of collection, and time series analysis methods are made as infrequently as possible. Significant changes have included:
25.31 For further details contact the Assistant Director, Labour Employer Surveys Section, on Perth (08) 9360 5245.