Thanks for the quick reply.  That makes sense, although I am still confused
why the functions prevent mincriterion from being lower than 0 as to run
cforests with "testtype" as "Teststatistic" and grow maximum depth trees you
need to put in qnorm(0) (= -inf) which is impossible?  I will stick to other
"testype"s as a work around for this.

Thanks again,
Matt

On 27 July 2010 16:34, Achim Zeileis <Achim.Zeileis@uibk.ac.at> wrote:

> On Tue, 27 Jul 2010, Matthew OKane wrote:
>
>  Hi,
>>
>> Could anyone help me understand how the mincriterion threshold works in
>> ctree and cforest of the party package?  I've seen examples which state
>> that
>> to satisfy the p < 0.05 condition before splitting I should use
>> mincriterion
>> = 0.95 while the documentation suggests I should use mincriterion =
>> qnorm(0.95) which would obviously feed the function a different value.
>>
>
> It depends on what the "testtype" is, which controls the criterion which is
> computed. For "Bonferroni"/"MonteCarlo"/"Univariate" the criterion is
>  1-pvalue
> while for "Teststatistic" it is a type of
>  z-statistic
>
> In the former case (default in ctree), a mincriterion of 0.95 or 0.99 etc
> is intuitive. In the latter case (default in cforest), a mincriterion of
> qnorm(0.9) or qnorm(0.95) etc. is natural.
>
> hth,
> Z
>
>  Thanks in advance,
>> Matthew
>>
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