11-06-2014 07:03 PM
This is probably a bit of a silly question, but I can't seem to find anything about this. I know in SPSS with other tests, a p value of 1.00 would mean absolute certainty and there is usually something that isn't quite right, but I'm not sure what a p value of 1 means in the output for negative binomial or if it is different in SAS. I have a two variables, plus the interaction between the two (which is what I'm interested in). Can anyone help me so I know how I should be interpreting this result or if there is something that I possibly did wrong that I need to redo?
11-07-2014 10:22 AM
If you are saying that you fit a negative binomial model including interaction, like this:
model y = x1 x2 x1*x2 / dist=negbin;
and that the p-value reported for the x1*x2 interaction was 1.0000, then this simply means that there is no evidence that the interaction parameter is nonzero.
11-07-2014 10:30 AM
If you have a database with lots of lots of observations the p-value (excuse my language) "don't mean shit".
It's going to be 1 no matter what you do. So in this particular case you'll have to find another type of measurement