Stock Series Holiday Regressors Generated from Flow Series Holiday Regressors

Abstract

Stock economic time series, such as end-of-month inventories, arise as the cumulative sum of monthly inflows and outflows over time, i.e., as accumulations of monthly net flows. In this article, we derive holiday regressors for stock series from cumulative sums of flow-series holiday regressors. This is similar to how stock trading day regressors have been derived. The stock holiday regressors from this approach have a very simple and appealing form when the flow regressors have standard properties. The modeling, forecasting and graphical results we present, for Easter effects in U.S. manufacturing inventories and for Chinese New Year effects in economic indicator inventory series of Taiwan, confirm the utility of this first general approach tomodeling stock holiday effects. As with estimated holiday effects fromflowseries,we find that stock holiday effects are usually larger than trading day effects but smaller than seasonal effects.

Keywords: inventory time series, seasonal adjustment, holiday effects, moving holidays, forecasting, Easter effects, Chinese New Year effects, X-12-ARIMA, X-13ARIMA-SEATS

JEL Classification: C82, C87