Seasonal adjustment is a means of removing the estimated effects of normal seasonal variation from the series so that the effects of other influences can be more clearly recognised.
In the seasonal adjustment of the livestock estimates, account has been taken of both normal seasonal factors and ‘trading day’ effects, where significant. Seasonal adjustment does not remove from the series the effect of irregular influences (e.g. abnormal weather, industrial disputes).
The state component series have been seasonally adjusted independently. Therefore, the adjusted components may not add to the Australian group totals.
For further information, see Time Series Analysis Frequently Asked Questions
The seasonal time series in this publication (Livestock Products, Australia) use the concurrent seasonal adjustment method up to and including June 2020 quarter. This means that seasonal factors were re-estimated each quarter, taking account of the latest available original estimates. This method improves the estimation of seasonal factors and, therefore, the seasonally adjusted and trend estimates for the current and previous months.
If not appropriately accounted for, unusual real-world events, such as COVID-19, can distort estimates calculated using this method. In such instances, a forward factor method may be employed.
From the September 2020 quarter, seasonal factors have been calculated using a forward factor method to ensure estimates are not distorted by COVID-19 impacts. From the September 2020 quarter to the June 2021 quarter, seasonal factors were calculated using data up to and including the June 2020 quarter, then projected from the September 2020 quarter onwards. From the September 2021 quarter, seasonal factors are being calculated using data up to and including the June 2021 quarter, then projected from the September 2021 quarter onwards.
When the concurrent seasonal adjustment method is reinstated, there may be revisions to seasonal series.
For more information about the updates to seasonal adjustment methods across ABS' economic statistics during the COVID-19 period, please refer to the ABS release: Methods changes during the COVID-19 period