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 ?
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