I think AbouEl-Makarim means "bimodal distribution" here is my solve
(sorry for primitive example)
m1<-0;
sd1<-1;
m2<-4;
sd2<-1;
bimodal<-curve(dnorm(x,m1,sd1)+dnorm(x,m2,sd2),
from=min(c(m1,m2))-3*max(c(sd1,sd2)),
to=max(c(m1,m2))+3*max(c(sd1,sd2)));
ql_1<-quantile(rnorm(1000,m1,sd1),0.05);
qh_1<-quantile(rnorm(1000,m1,sd1),0.95);
ql_2<-quantile(rnorm(1000,m2,sd2),0.05);
qh_2<-quantile(rnorm(1000,m2,sd2),0.95);
plot(bimodal$x, bimodal$y, type="l");
abline(v=ql_1, col="red",lwd=2);
abline(v=qh_1, col="red",lwd=2);
abline(v=ql_2, col="green", lwd=2);
abline(v=qh_2, col="green", lwd=2);
polygon(x=c(ql_1,qh_1, bimodal$x[bimodal$x<=qh_1 && bimodal$x>=ql_1]),
y=c(0,0,bimodal$y[bimodal$x<=qh_1 && bimodal$x>=ql_1]), col="gray");
polygon(x=c(ql_2,qh_2, bimodal$x[bimodal$x<=qh_2 && bimodal$x>=ql_2]),
y=c(0,0,bimodal$y[bimodal$x<=qh_2 && bimodal$x>=ql_2]), col="gray");
--
Zhan Chubukou
Chair of Pathological Physiology magistrant
Gomel State Medical University
Belarus
Just noticing that I read the post below too quickly and thought it
said "binomial" rather than "bimodal". But my solution works all the
same, you just need to provide a bimodal distribution as the first
argument. The only requirement is that if the name of your
distribution is "foo", then dfoo, pfoo, and qfoo need to exist and do
the correct things. They may be user defined functions.
You can of course, use the groups argument however you like to define
the tails of the distribution. For example, something like
groups = ( x < qfoo(0.05, ....) | x > qfoo(0.95) )
should shade the tails differently from the center.
In view of the email from Jeff Laux, I might consider adding some
utilities to build new dfoo, pfoo, and qfoo functions from existing
ones, at least for a few easy cases, like linear combinations. That
would make it really easy to generate various bimodal distributions.
---rjp
On Jan 15, 2012, at 2:41 PM, AbouEl-Makarim Aboueissa wrote:
Dear R users:
I am currently teaching a course in Statistics. Can someone give an
R code(s) to create a biomodal curve(s) with shaded area of 90% and
with 5% in each tail
With many thanks
abou
==========================
AbouEl-Makarim Aboueissa, Ph.D.
Associate Professor of Statistics
Graduate Program Coordinator
Department of Mathematics & Statistics
University of Southern Maine
96 Falmouth Street
P.O. Box 9300
Portland, ME 04104-9300
USA
Tel: (207) 228-8389
Fax: (207) 780-5607
Email: aabouei...@usm.maine.edu
aboue...@yahoo.com
Office: 301C Payson Smith
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