[R] Question about cochran test in R

[Henric Winell]

On 2015-05-07 09:15, Jim Lemon wrote:

> Hi Luis,
> Try this page:
>
> http://www.r-bloggers.com/cochran-q-test-for-k-related-samples-in-r/
>
> Jim

Cochran's Q test is a marginal homogeneity test, and such tests can be 
performed by the 'mh_test' function in the 'coin' package.  The 
following replicates the result in the blog post

 > library("coin")
 >
 > dta <- data.frame(
+     method    = factor(rep(LETTERS[1:4], 6)),
+     repellent = factor(c(1, 1, 0, 0,
+                          1, 1, 0, 1,
+                          1, 0, 0, 0,
+                          1, 1, 1, 0,
+                          1, 1, 0, 1,
+                          1, 1, 0, 1)),
+     fabric    = gl(6, 4, labels = as.roman(1:6))
+ )
 >
 > mh_test(repellent ~ method | fabric, data = dta)

	Asymptotic Marginal-Homogeneity Test

data:  repellent by
	 method (A, B, C, D)
	 stratified by fabric
chi-squared = 9.3158, df = 3, p-value = 0.02537


and uses the asymptotic approximation to compute the p-value.  The 
'coin' package also allows you to approximate the exact null 
distribution using Monte Carlo methods:

 > set.seed(123)
 > mh_test(repellent ~ method | fabric, data = dta,
+         distribution = approximate(B = 10000L))

	Approximative Marginal-Homogeneity Test

data:  repellent by
	 method (A, B, C, D)
	 stratified by fabric
chi-squared = 9.3158, p-value = 0.0202


For future reference, 'mh_test' is fairly general and handles both 
matched pairs or matched sets.  So, the well-known tests due McNemar, 
Cochran, Stuart(-Maxwell) and Madansky are just special cases.

For more general symmetry test problems, the 'coin' package offers the 
'symmetry_test' function and this can be used to perform, e.g., 
multivariate marginal homogeneity tests like the multivariate McNemar 
test (Klingenberg and Agresti, 2006) or the multivariate Friedman test 
(Gerig, 1969).


Henric



>
>
> On Thu, May 7, 2015 at 4:59 PM, Luis Fernando García
> <luysgarcia at gmail.com> wrote:
>> Dear R Experts,
>>
>> May be this is a basic question for you, but it is something I need really
>> urgently. I need to perform a Chi Square analysis for more than two groups
>> of paired observations. It seems to be ok For Cochran test. Unfortunately I
>> have not found info about  this test in R, except for dealing with outliers
>> which is not my aim. I am looking for something like this
>> https://www.medcalc.org/manual/cochranq.php
>>
>> I found a video to perform this analysis in R, but was not specially
>> useful. Does some of you know have some info about how to make this
>> analysis in R?
>>
>> Thanks in advance!
>>
>>          [[alternative HTML version deleted]]
>>
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>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> and provide commented, minimal, self-contained, reproducible code.
>