Hi, I am analyzing the relationship between animal density and several
environmental factors using GAM in mgcv. I used Poisson distribution and
quasi-Poisson model separately because there is overdispersion. In my model,
there is a categorical predictor variable "Year". However, when I compared the
outputs from Poisson and quasi-Poisson models, I realized that the standard
errors of "Year" from quasi-Poisson model were even a little smaller than those
from the Poisson model. Based on my knowledge, the standard errors of
quasi-Poisson regression coefficients should be larger than those from Poisson
model due to dispersion. Could anybody help me figure out what I was doing
wrong? Thank you very much!Hao
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