Put a normal curve on plot

Tue, Oct 31, 2006 2:06 PM

Here is some sample code that shows 2 different approaches, which you
want to use depends on what exactly you want to do and which will be
easier for you, the one draws the normal around the 6,7 point, the other
around the 3,4 point, change those values to do your plot:

plot(1:10, 2:11)

xx <- seq(-3,3,.1)

lines( 6+dnorm(xx,0,.75), 7+xx )

library(TeachingDemos)
subplot( plot(dnorm(xx),xx, type='l', axes=F,xlab='',ylab=''), 3,4,
hadj=0 )

Hope this helps,

Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Doran, Harold
Sent: Tuesday, October 31, 2006 6:26 AM
To: R-help at stat.math.ethz.ch
Subject: [R] Put a normal curve on plot

I would like to be able to place a normal distribution surrounding the
predicted values at various places on a plot. Below is some toy code
that creates a scatterplot and plots a regression line through the data.

library(MASS)
mu <- c(0,1)
Sigma <- matrix(c(1,.8,.8,1), ncol=2)
set.seed(123)
x <- mvrnorm(50,mu,Sigma)
plot(x)
abline(lm(x[,2] ~ x[,1]))

Say I want to add a normal distribution surrounding the predicted values
at the x-values of -1, 0, and 1. That is, at the points

\hat{y} = \mu + \beta_1(-1)
\hat{y} = \mu + \beta_1(0)
\hat{y} = \mu + \beta_1(1)

How might I go about doing this?

Harold

> version
               _                           
platform       i386-pc-mingw32             
arch           i386                        
os             mingw32                     
system         i386, mingw32               
status                                     
major          2                           
minor          4.0                         
year           2006                        
month          10                          
day            03                          
svn rev        39566                       
language       R                           
version.string R version 2.4.0 (2006-10-03)

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