I can see in the documentation on https://support.sas.com/kb/63/038.html that the Margins Macro does not work for zero-inflated models. Grateful for any advice on alternative approaches for ZIP models!
Excerpt from 63038:
LIMITATIONS: The Margins macro can be used only with a subset of the models available in PROC GENMOD since that procedure is used to fit the specified model. It cannot be used with multinomial or zero-inflated models available in GENMOD...
If the issue is that you have a large proportion of zero values, exceeding what the Poisson distribution allows, then you can try the negative binomial or the Tweedie distribution. The Tweedie distribution can handle large point masses at zero.
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.