I have used the following negtaive binomial model:
p3<-glm(formula = Infected ~ log(1 + PopDensity) + log(1 + GDPPPP)+ LifeExpectancy,family=negative.binomial(1),maxit=10000,data=df)
How can I justify the following questions?
What is the rationale behind the explanatory variables, log(1+Popdensity), log(1+GDPPPP)? Why do we need such unusual transformation for those variables?
What is the problem if we use Popdensity and GDPPPP as covariates?
My intention was to use log transformation because I had some countries like India with high population density. Some countries had very low population density. I don't know how to justify this log transformation. I appreciate your suggestions! Thanks!