Description

This paper is a methodological note focusing on helping to resolve two practical problems that typically the non specialized users confront when using the X-12-ARIMA seasonal adjustment program. First, we assess whether there is statistical evidence that seasonality is present in the time series under study and second, we evaluate the quality of the seasonal adjustment. We discuss some standard results of X-11 module in the X-12-ARIMA that are available in several handbooks. This paper, however, offers the advantage of going directly to the explanation of the practical solution of the two issues mentioned above, by analyzing practical cases and reproducing in a simple and comprehensive way the construction of the tests of presence of seasonality and the statistics of evaluation of seasonal adjustment.