[R] Paired sample t-test with mi.t.test
gagnonjoel24 at gmail.com
Sat Apr 8 16:53:53 CEST 2017
Dear Dr. Eichner and Dr. Kohl,
First, thank you for your response. I tried your code and R it worked
perfectly I just had to add: mi.t.test(implist*$imputation,* "pre_test",
"post_test", alternative = "greater", paired = TRUE, var.equal = TRUE,
conf.level = 0.95) for the code to run.
Thank you very much again for taking the time.
On Fri, Apr 7, 2017 at 3:26 PM, Prof. Dr. Matthias Kohl <
Matthias.Kohl at stamats.de> wrote:
> Dear Joel,
> are you trying to apply function mi.t.test from my package MKmisc?
> Could you please try:
> mi.t.test(implist, "pre_test", "post_test", alternative =
> "greater", paired = TRUE, var.equal = TRUE, conf.level = 0.95)
> x and y are the names of the variables, not the variables themselves.
> Am 06.04.2017 um 18:32 schrieb Joel Gagnon:
>> Dear all,
>> It is my first time posting on this list so forgive me for any rookie
>> mistakes I could make.
>> I want to conduct t-tests on a dataset that has been imputed using the
>> imput_pps <- mice(pps, m=20, maxit=20, meth='pmm') # pps is my dataset. It
>> contains items from an 11-item questionnaire gather at pre and post test.
>> So the data set has 22 columns.
>> I then proceed to compute the total scores for the pre and post test on my
>> imputed datasets:
>> long_pps <- complete(imput_pps, action ="long", include = TRUE)
>> long_pps$pre_test <- rowSums(long_pps[ ,c(3:13)])
>> long_pps$post_test <- rowSums(long_pps[ , c(14:24)])
>> I then used as.mids to convert back to mids object:
>> mids_pps <- as.mids(long_pps)
>> Next, I created an imputation list object using mitools:
>> implist <- lapply(seq(mids_pps$m), function(im) complete(mids_pps, im))
>> implist <- imputationList(implist)
>> Now, I want to conduct t-tests using the mi.t.test package. I tried the
>> following code:
>> mi.t.test(implist, implist$pre_test, implist$post_test, alternative =
>> "greater", paired = TRUE, var.equal = TRUE, conf.level = 0.95)
>> When I run this code, R tells me that Y is missing. I know this may sound
>> stupid, but I thought that I specified Y with this line: implist$pre_test,
>> implist$post_test - with implist$pre_test being X and implist$post_test
>> being Y - like I usually do for a normal t-test using the t.test function.
>> It seems I don't quite understand what the Y variable is supposed to
>> represent. Could someone help me figure out what I am doing wrong? You
>> help would be very much appreciated.
>> Best regards,
>> Joel Gagnon, Ph.D(c),
>> Department of Psychology,
>> Université du Québec à Trois-Rivières
>> Québec, Canada
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>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> PLEASE do read the posting guide http://www.R-project.org/posti
>> and provide commented, minimal, self-contained, reproducible code.
> Prof. Dr. Matthias Kohl
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