Hi again, OK let's see if this one qualifies as a bug: <hansl> clear T = 200 N = 20 len = T*N nulldata len --preserve setobs T 1:1 --stacked-time-series eval $panelpd # gives 0 </hansl> The zero $panelpd value is in contrast to the documentation, which says: "If the periodicity is not set in the active panel dataset, returns 1 in analogy to $pd for cross-sectional or undated data." In the meantime I have updated to the latest snapshot. thanks sven