# [R] simtest for Dunnett's test

Laurent Houdusse l.houdusse at cerep.fr
Fri Aug 13 14:16:59 CEST 2004

```However, on several tests, my results are correct:
The t-value seems always to correspond to the q'value calculated by
SigmaStat...

So,What do I have to use to find the same results as SigmaStat (value and
comparaison)?

Laurent Houdusse
Analyste Programmeur

-----Message d'origine-----
De : Liaw, Andy [mailto:andy_liaw at merck.com]
Envoyé : vendredi 13 août 2004 14:06
À : Laurent Houdusse; 'r-help at stat.math.ethz.ch'
Objet : RE: [R] simtest for Dunnett's test

Before you do any of that, you should realize the fact that simtest does
_not_ do Dunnett's test:  It can use `Dunnett' _contrasts_ to do comparisons
with a control, but the actual procedure is different.  You are unlikely to
get the same result as other packages that perform standard Dunnett's test
(or Tukey's, for that matter).

Andy

> From: Laurent Houdusse
>
> Hi!
>
> I use simtest fonction of multcomp package to compile a
> Dunnett's test.
> I have 10 treatments and one control group, so i create a matrix with:
>
> m<-matrix(0,10,11)
> m[1,1]<--1
> m[1,2]<-1
> m[2,1]<--1
> m[2,3]<-1
> m[3,1]<--1
> m[3,4]<-1
> m[4,1]<--1
> m[4,5]<-1
> m[5,1]<--1
> m[5,6]<-1
> m[6,1]<--1
> m[6,7]<-1
> m[7,1]<--1
> m[7,8]<-1
> m[8,1]<--1
> m[8,9]<-1
> m[9,1]<--1
> m[9,10]<-1
> m[10,1]<--1
> m[10,11]<-1
> rownames(m)<-c("vehicle+vehicle vs. morphne
> 60mg/kg+vehicle","vehicle+vehicle vs. Naloxone
> 30mg/kg+vehicle","vehicle+vehicle vs. Naloxone 30mg/kg+Morphine
> 60mg/kg","vehicle+vehicle vs. RWJ-69528-000-B
> 0.1mg/kg+vehicle","vehicle+vehicle vs. RWJ-69528-000-B
> 1mg/kg+vehicle","vehicle+vehicle vs. RWJ-69528-000-B 0.1mg/kg+morphine
> 60mg/kg","vehicle+vehicle vs. RWJ-69528-000-B 1mg/kg+morphine
> 60mg/kg","vehicle+vehicle vs. vehicle+acetaminophen
> 600mg/kg","vehicle+vehicle vs. RWJ-69528-000-B 0.1mg/kg+acetaminophen
> 600mg/kg","vehicle+vehicle vs. RWJ-69528-000-B 1mg/kg+acetaminophen
> 600mg/kg")
> y<-c(21.5,14.7,16.7,18.8,17.3,15.527,17.551,17.199,15.895,14.3
> 88,30,30,30,21
> .2,14.6,30.83,30.622,30.465,24.563,31.416,30,30,30,30,19.6,17.
> 61,30.346,20.8
> ,17.045,18.129,17.9,15.4,30,15.9,22.9,31.909,25.633,24.6,20.35
> 5,18.807,30,18
> .9,16.4,18.2,22.3,21.3,28.571,17.357,16.983,30.40,26.3,24.4,25
> ,24.1,14.4,10.
> 256,13.266,29.6,15.344,18.69,30,30,25.7,30,28.5,30,30.32,30,19
> .879,30.716,25
> .2,30,30,30,30,30,14.063,28.811,30.396,30.609,30,14.1,30,30,30
> ,26.322,30.386
> ,28.583,15.77,29.341,30,17.1,30,30,30,30,20.451,30,23.967,30.5
> 07,30,30,30,27
> .7,30,28.5,22.568,32.379,30.374,28.263)
> h<-factor(c(rep(1:11, each = 10)))
> result<-summary(simtest(y ~ h,cmatrix=cbind(0,m)))
> rownames(result\$estimate)
> result
>
>
> I want to compare my results with the results obtained with SigmaStat
> Software. In my results, i retrieve a correct q' value with the
> simtest t value How can i say if P<0.05 like the SigmStat results?
> Can i use p raw value, p bonf value, p adj value or other to compare
> directly? Or can i use the Dunnett's tables?
>
>
>
>
>
> Laurent Houdusse
> Analyste Programmeur
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
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>
>

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