Re: graph of overlapping normal distributions

[Steve Hodge <steve@nmr.mgh.harvard.edu>]

Mike,

Check the Sample Scripts directory that came with JMP.  There's a script
called "demoPlotProb.jsl" that contains the commands for plotting several
distribution functions (some interactive).

Here's a bare-bones version of the script for plotting a normal
distribution for two means and SDs (A and B) (i.e. two curves):

(start)
// Normal Density
A.mu = 0; A.sigma = 1;
B.mu = .5; B.sigma = 1.1;

NewWindow("Normal Density",
        Graph(
                FrameSize(500,300),
                XScale(-3,3),
                YScale(0,1),
                YFunction(Normal Density((x-A.mu)/A.sigma)/A.sigma,x),
                YFunction(Normal Density((x-B.mu)/B.sigma)/B.sigma,x)
        )
);
(end)

At least it's a starting point. You'll have to experiment to see if you 
can set line sizes and colors.

Steve



On Tue, 17 Jan 2006, Michael Bailey wrote:

> In order to demonstrate the concept of effect size to my class, I  
> want to show them two figures, each of overlapping normal  
> distributions. (Same mean differences, different variances, to show  
> why variance is part of effect size). jmp makes it very easy to  
> generate random normal data, although I haven't figured out yet how  
> to change the SD. More importantly, I can't figure out how to graph  
> two distributions on the same axes.
> 
> Thanks for any help.
> Mike Bailey
> 
> 
>