[R] Multiple sets of proportion tests
Allaisone 1
allaisone1 at hotmail.com
Sat Nov 25 00:35:55 CET 2017
Thank you for clarifying this point but my main question was about how to modify my code to do the analysis correctly. The code I mentioned :-
MyResults <- apply(Mydata, 2, function(x)prop.test(Mydata,c(200,100))
Results in this error : 'x' and 'n' must have the same length in the prop.test(x,n).
How can I modify "x' or "n" arguments so the analysis gives me the desired output
shown in my previous post ?
________________________________
From: Thierry Onkelinx <thierry.onkelinx at inbo.be>
Sent: 24 November 2017 21:06:39
To: Allaisone 1
Cc: r-help at r-project.org
Subject: Re: [R] Multiple sets of proportion tests
Hi anonymous,
?prop.test states that it returns a list. And one of the element is
'p.value'. str() on the output of prop.test() reveals that too. So
prop.test()$p.value or prop.test()["p.value"] should work.
Best regards,
ir. Thierry Onkelinx
Statisticus / Statistician
Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE
AND FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx at inbo.be
Kliniekstraat 25, B-1070 Brussel
www.inbo.be<http://www.inbo.be>
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2017-11-24 12:09 GMT+01:00 Allaisone 1 <allaisone1 at hotmail.com>:
>
> Hi all ,
>
>
> I have a dataframe of 200 columns and 2 rows. The first row in each column contains the frequency of cases in group I . The second row in each column contains the frequency of cases in group II. The frequency of trails is a fixed value for group I(e.g.200) and it is also another fixed values for group II (e.g. 100). The dataset looks like this :-
>
>
>> Mydata
>
>
> variable I variable II Variable III ......... 200
>
> Freq.of cases (gp I) 6493 9375 5524
>
> Freq. of cases (gpII) 509 462 54
>
>
>
> The result I need for the first column can be given using this code :
>
>
> MyResultsI <- prop.test(Mydata$variable I ,c(200,100))
> for the second column :-
> MyResultsII <- prop.test(Mydata$variable II ,c(200,100)) and so on ..
>
>
> I need to do the analysis for all columns and have only the columns with significant p-value results to be written in the the third row under each column so the final output has to be something like this :-
>
>
> variable I Variable III .........
>
> Freq.of cases (gp I) 6493 5524
>
> Freq. of cases (gpII) 509 54
>
> p-values 0.02 0.010
>
> Note, for example, that the 2nd column has bee removed as it resulted in a non-significant p-value result while col 1 and col 3 were included since p-value is less than 0.05.
>
> I'm not sure how to get the p-values only without other details but for the analysis itself , I believe it can be done with apply() function but its not clear to me how to specify the 2nd argument(n=samlpe sizes) in the prop.test.
>
> MyResults <- apply(Mydata, 2, function(x)prop.test(Mydata,c(200,100))
>
> How can I modify the "n" argument part to solve the issue of non-equivalent length between "x" and "n" ?. How can I modify this further to return only significant p-values results ?. Any help would be very appreciated ..
>
> Regards
>
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>
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