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!! Thanking you truly Prasanna> >----- Original Message ----- >From: "Dimitris Rizopoulos" <dimitris.rizopoulos at med.kuleuven.ac.be> >To: "Prasanna Balaprakash" <pbalapra at ulb.ac.be> >Cc: <r-help at stat.math.ethz.ch> >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" <pbalapra at ulb.ac.be> >> To: <r-help at stat.math.ethz.ch> >> 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. >>> >>> ______________________________________________ >>> R-help at stat.math.ethz.ch mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide! >>> http://www.R-project.org/posting-guide.html
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" <dimitris.rizopoulos at med.kuleuven.ac.be> >>To: "Prasanna Balaprakash" <pbalapra at ulb.ac.be> >>Cc: <r-help at stat.math.ethz.ch> >>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" <pbalapra at ulb.ac.be> >>>To: <r-help at stat.math.ethz.ch> >>>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. >>>> >>>>______________________________________________ >>>>R-help at stat.math.ethz.ch mailing list >>>>https://stat.ethz.ch/mailman/listinfo/r-help >>>>PLEASE do read the posting guide! >>>>http://www.R-project.org/posting-guide.html > > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Easy: First letter
"d" = density,
"p" = probability = cumulative distribution function (cdf),
"q" = quantile = inverse cdf,
"r" = pseudo-random number generation.
This is in, for example, "An Introduction to R". Are you
familiar
with "help.start()"? From an R command prompt (at least with recent
versions under Windows), this opens a web browser with a page offering
"manuals", "reference", and "Miscellaneous
Material". "An Intro to R"
is in the upper left. "Probability Distributions" is section 8.
hope this helps. spencer graves
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!!
>
>
>Thanking you
>truly
>Prasanna
>
>
>
>
>
>
>
>
>
>
>
>>----- Original Message -----
>>From: "Dimitris Rizopoulos" <dimitris.rizopoulos at
med.kuleuven.ac.be>
>>To: "Prasanna Balaprakash" <pbalapra at ulb.ac.be>
>>Cc: <r-help at stat.math.ethz.ch>
>>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" <pbalapra at ulb.ac.be>
>>>To: <r-help at stat.math.ethz.ch>
>>>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.
>>>>
>>>>______________________________________________
>>>>R-help at stat.math.ethz.ch mailing list
>>>>https://stat.ethz.ch/mailman/listinfo/r-help
>>>>PLEASE do read the posting guide!
>>>>http://www.R-project.org/posting-guide.html
>>>>
>>>>
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
>