Thanks, it really helps!
On Sat, May 1, 2010 at 2:34 PM, Ridgeway, Greg <gr...@rand.org> wrote:
> See friedman's paper "stochastic gradient boosting"
>
> Greg
>
> ------------------------------
> *From*: Changbin Du
> *To*: Ridgeway, Greg
> *Cc*: r-help@r-project.org
> *Sent*: Sat May 01 14:20:23 2010
> *Subject*: bag.fraction in gbm package
> Hi, Dear Greg,
>
> Sorry to bother you again.
>
> I have several questions about the 'gbm' package.
>
> if the train.fraction is less than 1 (ie. 0.5) , then the* first* 50% will
> be used to fit the model, the other 50% can be used to estimate the
> performance.
>
> if bag.fraction is 0.5, then gbm use the* random* 50% of the data to fit
> the model, and the other 50% data is used to estimate the predictive
> performance.
>
> Is my understanding for train.fraction and bag.fraction right? if not,what
> is the difference?
>
> can I set both fraction=1, and only use the cross.validation to select the
> iterations?
>
> Thanks so much!
>
> --
> Sincerely,
> Changbin
> --
>
>
>
> __________________________________________________________________________
>
> This email message is for the sole use of the intended...{{dropped:24}}
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