Re: [R] AIC function and Step function

Thank you, Kingsford. Then I am wondering if there are other ways to write R codes to calculate the "weights" ? Thanks! Dana Kingsford Jones wrote: > > On Sun, Nov 30, 2008 at 5:05 PM, Dana77 <[EMAIL PROTECTED]> wrote: >> >> Thanks for kind help from Steven and Christos last time. Now I

Re: [R] AIC function and Step function

On Sun, Nov 30, 2008 at 5:05 PM, Dana77 <[EMAIL PROTECTED]> wrote: > > Thanks for kind help from Steven and Christos last time. Now I got new > problem regarding the codes for calculating the "weights" (w) in "AIC () > function". > The original code is as below: > > getAnywhere("logLik.lm") > fu

Re: [R] AIC function and Step function

Thanks for kind help from Steven and Christos last time. Now I got new problem regarding the codes for calculating the "weights" (w) in "AIC () function". The original code is as below: > getAnywhere("logLik.lm") function (object, REML = FALSE, ...) { res <- object$residuals p <- ob

Re: [R] AIC function and Step function

Hi Dana, Many thanks to Christos Hatzis who sent me an offline response, pointing out the new functions that make this much easier than my last suggestions: methods() and getAnywhere() > methods("extractAIC") [1] extractAIC.aov* extractAIC.coxph* extractAIC.glm* extractAIC.lm* ext

Re: [R] AIC function and Step function

df) } extractAIC.aov <- extractAIC.lm extractAIC.negbin <- function(fit, scale, k = 2, ...) { n <- length(fit$residuals) edf <- n - fit$df.residual c(edf, -fit$twologlik + k * edf) } HTH Steven McKinney Statistician Molecular Oncology and Breast Cancer Program British C

[R] AIC function and Step function

I would like to figure out the equations for calculating "AIC" in both "step() function" and "AIC () function". They are different. Then I just type "step" in the R console, and found the "AIC" used in "step() function" is "extractAIC". I went to the R help, and found: "The criterion used is