Time-series data that are expected to be related and are conceptually similar. Such series are expected to be affected by similar factors. For example, an analyst could group series with similar causal forces. Although such series are typically correlated, correlation is not sufficient for series to be analogous. Statistical procedures (such as factor analysis) for grouping analogous series have not led to gains in forecast accuracy. See Duncan, Gorr and Szczyula (2001).

• Duncan, G., W. L. Gorr & J. Szczypula (2001), “Forecasting analogous time series,” in J. S. Armstrong (ed.), Principles of Forecasting. Norwell, MA: Kluwer Academic Press.