Prasanna Balaprakash wrote:
Dear R helpers:
Thanks for the previous reply. I am using Friedman racing test. According the the book "Pratical Nonprametric Statistic" by WJ Conover, after computing the statistics, he suggested to use chi-squared or F distribution to accept or reject null hypothesis. After looking into the source code, I found that R uses chi-sqaured distribution as below:
PVAL <- pchisq(STATISTIC, PARAMETER, lower = FALSE)
but still I cant figure out why they are using this pschisq insted of dchisq. Sorry I am wrong!!
You want to get the distribution function rather than the density.
Uwe Ligges
Thanking you truly Prasanna
----- Original Message ----- From: "Dimitris Rizopoulos" <[EMAIL PROTECTED]>
To: "Prasanna Balaprakash" <[EMAIL PROTECTED]>
Cc: <[email protected]>
Sent: Friday, January 21, 2005 1:05 PM
Subject: Re: [R] chi-Squared distribution
if you check ?qchisq, you'll see that the second
My mistake, the third argument
argument of the function denotes the non-centrality parameter! Try
qchisq(0.75, 1:3)
to get your answer.
Best, Dimitris
---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/336899 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
----- Original Message ----- From: "Prasanna Balaprakash" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, January 21, 2005 12:27 PM
Subject: [R] chi-Squared distribution
Dear Rs:
outer(1:3, 1:3, function(df1, df2) qf(0.95, df1, df2))
I compare this F distribution results with the table, the answers were perfect. But I need to see for chi-sqaured distribution. When I employed the similar formula
outer(1:3, 1:3, function(df1, df2) qchisq(0.95, df1, df2)) , I am getting unexpected results. I need to see the following values:
p=0.750 ..... 1 1.323
2 2.773
3 4.108
Thanking you Prasanna
Prasanna Balaprakash, Universit� Libre de Bruxelles, 50, Av. F. Roosevelt, CP 194/6, B-1050 Brussels, Belgium.
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