Use the S+Resample package. Then, some things that might be useful:
* you can specify the sample size for bootstrapping, see
help(sample.bootstrap)
* the crossValidation or bootstrapValidation functions.
Tim Hesterberg
>Good Day All,
>
>I am a newbie to SPLUS and had a question which I can't seem to figure
>out reading the documentation or searching the web.
>
>My goal is to create a generalized linear model using the negative
>binomial distribution. I created that model with the full dataset (~500
>sample points) and now that it is done, I wish to evaluate the
>robustness of the model. Conceptually what I would like to do is see
>how the coefficient estimates vary using the standard 80:20 rule. I
>create the model with 80% of the data, I would then take the 20% of the
>data I reserved to test the model, then I would repeat the procedure
>1000 times or so.
>
>Conceptually this is in essence a resampling technique and I thought I
>would be using the bootstrapping and/or jackknife methods in SPLUS.
>
>So two calls such as :
>
>l.nb <-glm.nb(formula = TC ~ TE + C + SQC + CINC + SQC.IN +
>offset(log(AP)), data = LD, na.action= na.omit, control =
>glm.control(maxit = 500))
>
>and then
>
>l.boot1 <- bootstrap(data=LD, statistic=coef(eval(l.nb$cal)), B=200)
>
>would in turn create my model and then resample my data 200 times (I set
>it to 200 so it would not take to long). What I can't seem to figure
>out is how to get the 80/20 split nor retaining the 20% for model
>validation.
>
>I have limited understanding of the SPLUS bootstrap/jackknife function
>and the documentation leaves me puzzled so I can't nail down the syntax.
>
>I know that this has been done (alot), am I on the right track here ?
>Could someone point me to some resources in SPLUS documentation and/or
>webpages that I could read up on before I ask more questions ?
>
>Thanks in advance !
>
>--
>
>-Don
>
>Don Catanzaro, PhD Landscape Ecologist
>dgcatanzaro@gmail.com 16144 Sigmond Lane
>479-751-3616 Lowell, AR 72745
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