I am running GLM models using the gamma family.  For example:
model <-glm(y ~ x, family=Gamma(link="identity"))

I am getting different results for the normal Q-Q plot and the
Scale-Location plot if I run the diagnostic plots without specifying the
plot vs. if I specify the plot ... e.g., "plot(model)" gives me a different
Normal Q-Q graph than "plot(model, which=c(2))".  The former gives data
points distributed in a quadratic pattern, while the latter gives data
points more or less along the 1:1 line.  Shouldn't these two commands be
giving me the same exact graphs?  I have read the documentation on plot.lm
and searched the help archives, but I am still learning GLM's and I'm not
very familiar with understanding diagnostic plots for GLM's, so any help
would be much appreciated!

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