[R] dnorm and qnorm
gunter.berton at gene.com
Sat Nov 13 00:01:36 CET 2010
There is no "reversing the dnorm function" -- dnorm is many to one in
general (in the normal case, 2 to 1 except for the mean). How would
you "reverse" dunif, for example?!
However, with that understanding you could do a simple one dimensional
search within the range you want via optimize(), as in
> optimize(function(x)abs(dnorm(x) - .3286),lower=-5,upper = 0) ## or use squared error
On Fri, Nov 12, 2010 at 2:35 PM, Edwin Sun <csun at cfr.msstate.edu> wrote:
> Hello all,
> I have a question about basic statistics. Given a PDF value of 0.328161,
> how can I find out the value of -0.625 in R? It is like reversing the dnorm
> function but I do not know how to do it in R.
>> pdf.xb <- dnorm(-0.625)
>  0.328161
>  -0.444997
>  0.628605
> Many thanks,
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> and provide commented, minimal, self-contained, reproducible code.
Genentech Nonclinical Biostatistics
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