Source: MIL-OSI Submissions
Impact of COVID-19 on seasonally adjusted and trend series – methods paper
15 September 2020
This page describes how COVID-19 has impacted seasonal adjustment, and why Stats NZ has temporarily suppressed publication of selected time series.
What are seasonally adjusted and trend time series?
In the seasonal adjustment process, the actual value is broken down into three components: trend for medium to long-term movements, seasonal for systematic annual effects, and irregular for short-term unsystematic fluctuations.
The seasonally adjusted values allow us to compare different periods without seasonality contributing to the differences. Trend time series are useful to compare data points against previous peaks and troughs, as well as indicate the direction of the series.
To read this paper on our website, visit: