In an effort to promote the idea of best practices in seasonal adjustment, the European Statistical System (ESS) and Central Banks with significant statistical departments have produced a set of guidelines to assist all levels of seasonal adjustment practitioners from novices to experts.

These guidelines focus the technical framework on two approaches: TRAMO-SEATS (supported by Banco de España) and X-12-ARIMA (supported by the Bureau of Census in the US) which are the most commonly used within the ESS. This document does not discuss their relative merits as both can be considered equally valuable (as is reflected in their widespread use).

The guidelines are not just restricted to the seasonal adjustment alone, they also cover the pre-treatment of series, revision policies, quality, documentation and specific issues related to limitations of seasonal adjustment, e.g. short time series.

Throughout this document, the reader will be presented with a step by step process with explanations and reasons as to which options to take either when analysing individual series or when adjusting a large number of series for production purposes.

Custodian: Eurostat