New Techniques for Determining if a Time Series Can Be Seasonally Adjusted Reliably and Their Application to U.S. Foreign Trade Series

Written by:
RR84-30

Introduction

Deciding when a series is a good candidate for seasonal adjustment can be difficult. There are situations where a series may show evidence of seasonality, but because a dominating irregular component, for example, or a volatile seasonal component, many of its seasonal factors cannot be estimated reliably. In these circumstances, the estimates of a given month's seasonal factor can change substantially when more data are added to the series and earlier data deleted.

Page Last Revised - October 28, 2021