On Thu, 3 Nov 2016, Allin Cottrell wrote: Second response: OK, I can confirm that the "pca" command used to skip rows in the dataset on which there were missing values (in gretl version 1.9.*), but in current gretl missing values provoke an error. This isn't a bug, as such, but it may not be a well considered change in behavior. I think the motivation for the change may have been related to the fact that under the old behaviour there was no indication of the number of missing observations that were dropped. But of course that could be fixed by printing a count of observations actually used (or dropped), rather than rejecting a sample containing missing observations. Thoughts from other users on this? Allin Cottrell