[R] horsekicks

[Göran Arnoldsson]

A log-linear fit with offset and linear predictor that reflects the 
Poisson hypothesis does it:

 > glm(years~offset(log(sum(years))-lgamma(deaths+1))+deaths,family=poisson)

...

Coefficients:
(Intercept)       deaths 
    -0.6100      -0.4943 

Degrees of Freedom: 6 Total (i.e. Null);  5 Residual
Null Deviance:        36.23
Residual Deviance: 0.8668     AIC: 27.34

...

Note that the intercept estimates mu directly whereas the slope does 
this indirectly: exp(-0.4943) = 0.6099978.
More details can be found in J.K. Lindsey: "Applying Generalized Linear 
Models", Springer, 1997, ch. 3.

Göran Arnoldsson
Deapartment of statistics
Umeå University
Sweden


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