Seasonal Adjustment of Daily Series of Credit Card Purchases

Abstract

In 2020, as part of a project of promoting rapid economic indicators during the COVID-19 period, a statistical procedure for seasonal adjustment of daily credit card purchases was developed in the Bank of Israel, based on data transmitted by Shva to the Bank of Israel on a daily basis.The operational importance of the credit card purchases indicator has increased again during the current crisis that erupted on October 7th, 2023, and that resulted in a significant slowdown in economic activity.Our statistical procedure decomposes a daily series using STL-functions into a trend component and three seasonal components, with weekly, monthly and annual cycles. The practical results of this decomposition are quite similar to the results of other procedures reviewed in this article. Specially developed steps of this procedure are the imputation of missing data on Saturday's purchases, and prior adjustment for Jewish holidays, which in recent years have also coincided with periods of crisis.

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