I am trying to shade the critical regions for normal distribution with different means and making overlaps of the plots to explain Type I and Type II errors. I tried the following. If I calculate the z score and as I did below, can I use it to pick regions from the original data? I think I am making mistake by calculating the z scores for d$x, can someone explain the mistake I am making?
left<- -1.96 right<- 1.96 mu1<-rnorm(100000,20,5) d<-(density(mu1)) x.tmp<-d$x y.tmp<-d$y x<-x.tmp y<-y.tmp mu1z<-(x.tmp-mean(x.tmp))/sd(x.tmp) # is it correct? a<-which(mu1z <=left) b<-which(mu1z >=right) plot(x.tmp,y.tmp, type="l") polygon(x=c(x.tmp[a],rev(x.tmp[a])),y=c(y.tmp[a],rep(0,length(y.tmp[a])) ),col="gray90") polygon(x=c(x.tmp[b],rev(x.tmp[b])),y=c(y.tmp[b],rep(0,length(y.tmp[b])) ),col="gray90") -----Original Message----- From: Stephen Tucker [mailto:[EMAIL PROTECTED] Sent: Thursday, August 02, 2007 3:11 PM To: Nair, Murlidharan T; r-help@stat.math.ethz.ch Subject: RE: [R] t-distribution yes, or p <- seq(0.001,0.999,,1000) x <- qt(p,df=9) y <- dt(x,df=9) plot(x,y,type="l") f <- function(x,y,...) { polygon(x=c(x,rev(x)),y=c(y,rep(0,length(y))),...) } with(data.frame(x,y)[x >= 2.3,],f(x,y,col="gray90")) with(data.frame(x,y)[x <= -2.3,],f(x,y,col="gray90")) --- "Nair, Murlidharan T" <[EMAIL PROTECTED]> wrote: > > I tried doing it this way. > > left<--2.3 > right<-2.3 > p <- seq(0.001,0.999,,1000) > x <- qt(p,df=9) > y <- dt(x,df=9) > plot(x,y,type="l") > x.tmp<-x > y.tmp<-y > a<-which(x<=left) > polygon(x=c(x.tmp[a],rev(x.tmp[a])),y=c(y.tmp[a],rep(0,length(y.tmp[a])) ),col="gray90") > b<-which(x>=right) > polygon(x=c(x.tmp[b],rev(x.tmp[b])),y=c(y.tmp[b],rep(0,length(y.tmp[b])) ),col="gray90") > > Please let me know if I have made any mistakes. > Thanks ../Murli > > > > -----Original Message----- > From: Richard M. Heiberger [mailto:[EMAIL PROTECTED] > Sent: Thu 8/2/2007 10:25 AM > To: Nair, Murlidharan T; Stephen Tucker; r-help@stat.math.ethz.ch > Subject: Re: [R] t-distribution > > I believe you are looking for the functionality I have > in the norm.curve function in the HH package. > > Download and install HH from CRAN and then look at > > example(norm.curve) > > ________________________________________________________________________ ____________Ready for the edge of your seat? Check out tonight's top picks on Yahoo! TV. http://tv.yahoo.com/ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
