Am 25.07.2025 um 21:30 schrieb Cottrell, Allin:
 It's more specific than I indicated: things go wrong as soon as a
 lagged regressor /that is not the last regressor at the time/, gets 
 omitted.
 The regressors will have been reordered, if necessary, at the start of 
 the backward stepwise procedure, to increase the likelihood that terms 
 to be omitted will come at the end, which simplifies things 
 considerably. But that's not going to work 100%. When we have to 
 eliminate an "internal" column of Q, and row/column of R, the 
 recomputation that's needed involves reference to the dataset, but at 
 what starting point? We were diving in at dset->t1, but in a 
 specification with lags it should be at orig->t1, where @orig is the 
 original model. That's a distinction without a difference in the case 
 of cross-sectional data, but it's crucial for time series with 
 lags.Now that's fixed in git. 
Thanks, Allin! I tested with the latest snapshot and everything seems 
fine now!
cheers
sven