Dear Allstat users,

I have two very general questions about Poisson Regression Analysis.

I am relatively new to this topic but I tried to document myself as much as I could. The explanations I found in the web were too incomplete or too difficult for me.

The two questions are:



1. Given a response variable Y and n explanatory variables X1, ..., Xn, drawing a plot for each Xi against Y can I already draw some preliminary conclusions? (i.e. I can understand that I likely get rid of an explanatory variable or I likely need a polynomial regression for an explanatory variable or a transformation is needed, ...)

2. Given a dummy variable XD, I can simply add it to the other explanatory variables or I can link it to a particular explanatory variable Xi. How can I understand the right choice? And in the second case, how can I understand to which explanatory variable Xi I should link XD?



I hope that somebody can give me some useful hints.



Thank you for your help

Stefano Sofia



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