Hi,
In the result shown, the District 1 is used as the base category. How to
change to make District 4 as a base category ?
On Mon, Feb 23, 2009 at 11:05 AM, choonhong ang <angie.bear...@gmail.com>wrote:
> I have used the insurance data from R library and I have 2 questions:
> I use the following:
> >library(MASS)
> >data(Insurance)
> > m1=glm(Claims ~ District + Group + Age + offset(log(Holders)),data =
> Insurance, family = poisson)
> >summary(m1)
>
> Call:
> glm(formula = Claims ~ District + Group + Age + offset(log(Holders)),
> family = poisson, data = Insurance)
> Deviance Residuals:
> Min 1Q Median 3Q Max
> -2.46558 -0.50802 -0.03198 0.55555 1.94026
> Coefficients:
> Estimate Std. Error z value Pr(>|z|)
> (Intercept) -1.810508 0.032972 -54.910 < 2e-16 ***
> District2 0.025868 0.043016 0.601 0.547597
> District3 0.038524 0.050512 0.763 0.445657
> District4 0.234205 0.061673 3.798 0.000146 ***
> Group.L 0.429708 0.049459 8.688 < 2e-16 ***
> Group.Q 0.004632 0.041988 0.110 0.912150
> Group.C -0.029294 0.033069 -0.886 0.375696
> Age.L -0.394432 0.049404 -7.984 1.42e-15 ***
> Age.Q -0.000355 0.048918 -0.007 0.994210
> Age.C -0.016737 0.048478 -0.345 0.729910
> ---
> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> (Dispersion parameter for poisson family taken to be 1)
> Null deviance: 236.26 on 63 degrees of freedom
> Residual deviance: 51.42 on 54 degrees of freedom
> AIC: 388.74
> (1) In the result above, what is Group.L, Group.Q, Group.C, Age.L, Age.Q,
> Age.C ?
>
> (2) When I copy the Insurance data in csv format (as shown in the
> attachement) and run the same procedure the result shown is different from
> above result, why ?
>
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
