[R] (1-alpha)th percentile

[Ben Bolker]

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