我在做logistic的时候，出现了这样的警告，求高人帮助解答！There are 154 (48.7%) cells (i .e. dependent variable levels by subpopulations ) with zero frequencies.
Unexpented singularifiles in the Hassian matrix are encountered. This indicates that either some predictor variables should be excluded or some categories should be merged.
The NOMERG procedures continues despite the above warning. Subsequent results shown are based on the last iteration . Validity of the model fit is uncertain.