From: Spencer Graves <spencer.graves_at_pdf.com>

Date: Thu 29 Jul 2004 - 16:20:58 EST

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jul 29 16:40:29 2004

Date: Thu 29 Jul 2004 - 16:20:58 EST

The function "as.vector" will remove the names:

> t.test(1:9)$statistic

t

5.477226

> as.vector(t.test(1:9)$statistic)

[1] 5.477226

Is this what you want? spencer graves

Michael Rennie wrote:

>Hi, there

*>
**>I am quite sure there is an easy answer to this, but I am unsure how to gather
**>a bunch of t-statistics in an organized format.
**>
**>I am trying to generate a list of t-statistics for a randomization routine. If
**>I try to collect a bunch of t-statistics from a run, this is what happens:
**>
**>
**>
**>
**>>M <- 10 ; simt <- NULL
**>>for(i in 1:M)
**>>
**>>
**>+ {
**>+ perm<-sample(site,replace=F)
**>+
**>+ permute<-cbind(perm, site, a, b, c)
**>+
**>+ m<- order(perm)
**>+
**>+ m1<-cbind(perm[m], site[m], a[m], b[m], c[m])
**>+
**>+ black<-c((m1[1:5,5]),(m1[11:15,5]))
**>+ #black
**>+
**>+ white<-c((m1[6:10,5]),(m1[16:20,5]))
**>+ #white
**>+
**>+ sims <- t.test(black,white,var.equal=FALSE,mu=0)$statistic
**>+ simt<-c(simt,sims)
**>+ #simt
**>+ } # Next i (next simulation)
**>
**>
**>>simt
**>>
**>>
**> t t t t t t t
**> 0.3474150 0.1542973 -0.4044992 1.2466663 -0.2933944 -0.5809257 0.7799080
**> t t t
**>-1.4132713 1.2048335 -0.6596936
**>
**>Which gives me a list, but not in a form that I can do anything with. This is
**>in stark contrast to what happens when requesting p-values, which gives output
**>like this:
**>
**>
**>
**> M <- 10 ; simt <- NULL
**>
**>
**>>for(i in 1:M)
**>>
**>>
**>+ {
**>+ perm<-sample(site,replace=F)
**>+
**>+ permute<-cbind(perm, site, a, b, c)
**>+
**>+ m<- order(perm)
**>+
**>+ m1<-cbind(perm[m], site[m], a[m], b[m], c[m])
**>+
**>+ black<-c((m1[1:5,5]),(m1[11:15,5]))
**>+ #black
**>+
**>+ white<-c((m1[6:10,29]),(m1[16:20,5]))
**>+ #white
**>+
**>+ sims <- t.test(black,white,var.equal=FALSE,mu=0)$p.value
**>+ simt<-c(simt,sims)
**>+ #simt
**>+ } # Next i (next simulation)
**>
**>
**>>simt
**>>
**>>
**> [1] 0.6763749 0.7480091 0.9447851 0.3342029 0.7852635 0.3199006 0.5272153
**> [8] 0.3863616 0.7333693 0.7268907
**>
**>Now THAT'S what I'd like to get for my t-statistics- a nice vector (simt) that
**>I can deal with later, rather than the output I am currently getting (the first
**>output above).
**>
**>Does anyone know a way to extract JUST the t-statistics from the t.test,
**>without the "t" character header, so I can generate a nice little vector?
**>Alternatively, can I manipulate the output I am currently getting for the t-
**>statistics so that I can isolate just the numbers?
**>
**>
**>
*

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jul 29 16:40:29 2004

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