Sounds like homework (you are not supposed to post homework-related
questions here - read the guidelines). But anyway:
nr.of.rejections=0
for(i in 1:10000){
x=rnorm(10, 0.1, 1)
result<-t.test(x,alternative="greater",mu=0,conf.level=0.95)$p.value
if(result<0.05) nr.of.rejections = nr.of.rejections+1
}
print(paste("Observed number of rejections of Ho:", nr.of.rejections,
sep="
"))
observed.rejection.rate = nr.of.rejections/10000
print(paste("Actual rejection rate of Ho:", observed.rejection.rate,
sep="
"))
However, it's not Type 1 error rate. It's the observed rejection rate.
Type
1 error is probability of rejecting Ho when it is actually TRUE. And in your
case (x = rnorm(10,0.1,1) your null hypothesis (that mean = 0) is NOT true
because,as you know, in the population the mean is 0.1.
Dimitri
On Wed, May 5, 2010 at 2:31 PM, level <lev_lambert@hotmail.co.uk> wrote:
>
> I have been set a question which i understand statistically but my
> inability
> with R is preventing me from finishing it..
>
> My question is that we to calculate the frequency of Type 1 errors
>
> starting with x = rnorm(10, 0.1, 1)
>
> then doing a t-test seeing whether you reject the null hypothesis (Ho mu
> > 0) alternative is mu > 0
>
> Then i am supposed to use a for loop to do this procedure 10 000 times
> keeping track whether the null has been rejected or not. If anyone can
> help
> with me it would be great help
>
> cheers
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/T-test-for-loop-tp2131458p2131458.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
--
Dimitri Liakhovitski
Ninah.com
Dimitri.Liakhovitski@ninah.com
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