Seasonal adjustment of Irish official statistics during the COVID-19 crisis

Abstract

As experienced worldwide, the COVID-19 outbreak has had a severe impact on Irish society and the economy. The impact of the pandemic is evident in most of the Irish infra-annual socio-economic times series statistics. In terms of seasonal adjustment these effects cannot be ignored. The COVID-19 effects on time series data need to be identified and treated to ensure that seasonally adjusted data is trustworthy, accurate and reliable. Dealing with the COVID-19 effects poses both statistical and logistical challenges. The Central Statistics Office (CSO) in Ireland has taken a pro-active approach to seasonal adjustment during this crisis, using intervention models from the onset of the pandemic. Adopting intervention models from the beginning of the pandemic provides meaningful real-time statistics to our users as the impact of this crisis unfolds and will hopefully avoid large scale future revisions. This paper outlines the statistical framework that underpins our seasonal adjustment response and describes how the CSO responded to the COVID-19 crisis in terms of seasonal adjustment.