[R] chi2

Ben Bolker bolker at ufl.edu
Wed Oct 10 13:49:10 CEST 2007




elyakhlifi mustapha wrote:
> 
> Hello,
> I want to use the quantile function so I read the doc but I don't
> understand with this
> 
>> qchisq(seq(0.05,0.95,by=0.05),df=(length(don)-1))
>  [1] 62667.11 62795.62 62882.42 62951.47 63010.74 63064.00 63113.39
> 63160.27 63205.65 63250.33 63295.04 63340.48 63387.48 63437.03 63490.53
> 63550.14 63619.68
> [18] 63707.24 63837.16
> 

  I don't understand what your question is.  I infer that don is a vector
of length 63252:

1. find df to match the first result in the vector;

> uniroot(function(d) pchisq(62667.11,df=d)-0.05, c(1000, 1e9))
$root
[1] 63251

$f.root
[1] -1.483395e-11

$iter
[1] 28

$estim.prec
[1] 0.0001207690

recreate the results:

> qchisq(seq(0.05,0.95,by=0.05),df=63251)
 [1] 62667.11 62795.62 62882.42 62951.47 63010.74 63064.00 63113.39 63160.27
 [9] 63205.65 63250.33 63295.04 63340.48 63387.48 63437.03 63490.53 63550.14
[17] 63619.68 63707.24 63837.16

   So what's the problem?

  Ben Bolker

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