The authors demonstrate that the recommendations for analyzing productivity in the appendix to the ISO/IEC 15939 standard are inappropriate. They also show that problems with the ISO/IEC advice can be compounded if software engineers attempt to apply statistical process-control techniques to software productivity metrics. They recommend using small meaningful data sets as the basis for productivity analysis and using effort-estimation models to assess productivity rather than productivity metrics.This article is part of a special focus section on software metrics.