SUSPENSION OF TREND SERIES AND CHANGES TO SEASONAL ADJUSTMENT DURING THE COVID-19 PERIOD
Time series and sudden changes in the labour market
Trend and seasonally adjusted Labour Force Survey estimates are important for understanding the current state of the labour market, and providing medium and long-term signals.
However, unusual, sudden and/or extreme changes in the labour market (e.g. changes to regular and seasonal patterns in employment, working hours, job search or availability as a result of COVID-19) can be difficult to account for in the short-term in both seasonal adjustment and trend estimation processes.
The ABS has been monitoring the impacts from COVID-19 on labour force time series, and has made the following changes to trend and seasonally adjusted estimates.
Suspension of trend estimates
The Labour Force trend series have been suspended from April 2020, until more certainty emerges in the underlying trend in labour market activity over the COVID-19 period. This is in recognition of the time series shocks in the labour market between the March 2020 and April 2020 data points. While trend estimates are generally the best measure of the underlying behaviour of the labour market, any large changes in the labour market as a result of COVID-19 will likely make it difficult to estimate a reliable short-term indicator of the trend.
Existing spreadsheets containing trend, seasonally adjusted and original data will continue to be published in the same format, however trend columns will be populated with ‘nca’.
For the NT and ACT, seasonally adjusted data will be published in separate spreadsheets for the duration of time that the trend series are suspended.
Changes in the seasonal adjustment process
During the COVID-19 period the ABS will use forward seasonal factors to produce seasonally adjusted estimates, rather than the standard concurrent seasonal factors method. The forward factors approach is better suited to managing large movements at the end point of series and will ensure that large movements do not have a disproportionate influence on the seasonal factors.
For a more detailed discussion on the implications of unusual events on time series, see When it's not "business-as-usual": Implications for ABS Time Series.
Once further data are available, trend and/or seasonal breaks may be estimated and applied to improve published labour force time series estimates.
The ABS will also provide regular updates on the status of trend and seasonally adjusted estimates, with a view to returning to concurrent seasonal factors at the most appropriate point.
For further information on the impact of COVID-19 on labour force time series, or on labour force statistics more generally, please email firstname.lastname@example.org.