[R] Problems with generalized linear model (glm) coefficients.

Lucas
Wed, 07 Mar 2012 13:34:09 -0000

Hello to everyone.

I´m writing you because I´m feeling a bit frustrated with my work.

My work consists in finding  the relation between the amount of fires and
the weather, so, my response variable is the amount of fires in a fire
season and the explanatory variables are the temperature, the amount of
precipitation and the some others…. my problem is this; I keep getting the
wrong sign in the coefficients estimated, I get a negative sign for
temperature and a positive sign for precipitation, which is unreasonable,
the greater the temperature I would expect more fire, on the contrary, the
greater the precipitation I would expect less fires.  So far I have deal
with overdispersion, multicollinearity  and the amount of zeroes through
passing from Poisson to Negative Binomial and Hurdle.  I believe I have
used all my options and still have the wrong signs on my coefficients.

Do I have more options? What does it mean that I keep getting those signs?

If anyone could help me I would really appreciate it.

Thank you.


Lucas.

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