simulation of levene's test
On Mon, May 28, 2012 at 12:14 PM, ?zg?r Asar <oasar at metu.edu.tr> wrote:
Dear Dila, Try the following: library(Rcmdr)
Or avoid the unncessary overhead of Rcmdr and use library(car) to provide levenTest instead.
asim <- 1000 pv<-NULL
It's also many orders of magnitude more efficient to preallocate "pv"
and then simply put things "into" it.
pv <- vector("real", 1000)
for(i in 1:asim)
{
print(i)
set.seed(i)
Setting the seed each loop seems excessive but I suppose it's a matter of taste.
g1 <- rnorm(20,0,2) g2 <- rnorm(20,0,2) g3 <- rnorm(20,0,2) x <- c(g1,g2,g3)
Is there any reason not to do this as x <- rnorm(60, 0, 2)
group<-as.factor(c(rep(1,20),rep(2,20),rep(3,20)))
and this as as.factor(rep(1:3, each = 20))
pv<-c(pv,leveneTest(x,group)$"Pr(>F)"[1])
Once you preallocate pv change this to pv[i] <- leveneTest(x, group)$"Pr(>F)"[1] But it's even better not to use the dollar sign shortcut here (defensive programming and all that -- particularly with nonstandard names which I'm pretty sure won't give a big error here but will elsewhere) pv[i] <- leveneTest(x, group)[["Pr(>F)"]][1] And even better would be to do this all using the "replicate" function, but I'll leave that as an exercise to the reader. Michael
} Best Ozgur ----- ************************************ Ozgur ASAR Research Assistant Middle East Technical University Department of Statistics 06531, Ankara Turkey Ph: 90-312-2105309 http://www.stat.metu.edu.tr/people/assistants/ozgur/ -- View this message in context: http://r.789695.n4.nabble.com/simulation-of-levene-s-test-tp4631578p4631600.html Sent from the R help mailing list archive at Nabble.com.
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