Re: [R] Normal distribution with R

Hi James, (qnorm(.9)-qnorm(.1)) is the width of the 80% CI of a standard normal distribution. So its a kind of standardization the other way round calculating sd from this. The same holds for arbitrary p1 and p2. Without loss of generality (since the normal distribution is symmetric), assume

Re: [R] Normal distribution with R

Hi James its just simple calculus, since with q90<-qnorm(.9,me,sd) q10<-qnorm(.1,me,sd) mean<-(q90+q10)/2# the normal distribution is symmetric around the mean sd<-(q90-q10)/ (qnorm(.9)-qnorm(.1)) # between 10th and 90th are qnorm(.9)-qnorm(.1)=2.563103sds hth. g...@ucalgary.ca schrieb:

[R] Normal distribution with R

If we knew two pth quantiles for a normal distribution, is it possible that we can find mean and sigma for the normal distribution using R? Let x ~ norm(mean, sigma). Suppose that qnorm(0.9,mean,sigma) and qnorm(0.1,mean,sigma) are known. Can we find mean and sigma using R? Thanks, -james _