Re: [R] (1-alpha)th percentile

From: Ben Bolker <bolker_at_ufl.edu>
Date: Fri, 16 May 2008 13:35:05 +0000 (UTC)

hanen <hanen.mastouri <at> yahoo.fr> writes:

>
>
> hello;
> firstly, my gratitude to all who help me to find a function that allows me
> to add confidence interval to my graph.
> in order to calculate the (1-alpha)th percentile of for exemple an
> F(df1,df2) distribution i do like this:
> v<-df(alpha,df1,df2)
> percentile<-qf(v,df1,df2,alpha)
>
> if it is true please alert me , and if it is not what should do then?
>
> :handshake:

   I think it's just qf(1-alpha,df1,df2)

   To use a well-known example:
qnorm(0.975) = 1.959964
(in this case, for a two-tailed test, you need 1-alpha/2 , but F is one-tailed so that's no problem.

  Ben Bolker



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