search for: overdipersed

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2003 Apr 22
0
Correct SE in a poisson model.
...rplot with mean and SE of mean. So I have: The mean: > tapply(slugs,field,mean) Nursery Rookery 1.275 2.275 The SE: > tapply(slugs,field,sd)/sqrt(tapply(slugs,field,length)) Nursery Rookery 0.3651264 0.3508004 If the data has been normally distributed it is correct, but it is overdipersed count data. I make a model > m.poisson <- glm(slugs~field,family=quasipoisson) And I have these coefficients: Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 0.2429 0.2490 0.976 0.3323 fieldRookery 0.5790 0.3112 1.861 0.0666 . The e...