02-27-2012 09:41 PM
Seasonality is mostly tested for time series data. You should read about SAS-ETS - Overview of the Time Series Forecasting System
also look at proc SPECTRA for an alternate way of detecting seasonality.
SAS-ETS is a separate product from SAS-STAT.
03-01-2012 03:44 PM
You might be interested in this SAS Global Forum paper: http://www.lexjansen.com/wuss/2004/posters/c_post_alternative_seasonali.pdf, featuring PROC X12.
In addition this example might be useful: http://support.sas.com/rnd/app/da/new/801ce/ets/chap5/sect21.htm