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Re: st: RE: three mean and sd plots on the same graph?


From   Joseph Wagner <joseph.wagner@wright.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: three mean and sd plots on the same graph?
Date   Thu, 08 Nov 2007 09:01:17 -0500

Unfortunately I can't use over with -stripplot- since I can't combine ()over with more than one variable and I have three that I wanted to compare side by side for each value of the X- axis categorical variable. by() won't work either for that matter since what I want is basically X over many Y as follows with a crude representation of my boxplot:


|
| - - - -
| +-+ - +-+ +-+ - +-+
| |-| +-+ |-| |-| +-+ |-|
| +-+ |-| +-+ +-+ |_| +-+
| - +-+ - - +-+ -
| - -
+-------------------------------------------
var_1 var_2 var_3 var_1 var_2 var_3
age=8 age=9


I don't have access to the article Maarten referenced.




Nick Cox wrote:

Now my best advice is to use -stripplot- from SSC. Its default is to
show strips of data points, but you can jitter or stack and add boxes or
bars.
. sysuse auto
(1978 Automobile Data)
. stripplot trunk turn mpg, bar

. stripplot trunk turn mpg, bar
. stripplot trunk turn mpg, bar vertical

You can use a -by()- option as well. I'd recommend showing the data, but you can blank it out with -ms(none)-.
By default the bars are offset from the data which may answer your last question.
Joseph Wagner

I created box plot graph with of 3 X variables over the same Y variable but was then asked to produce a similar graph this time using mean (not median) and +/- 95% CI. I don't think Stata can do this but thanks to a post by Nick three years ago, I was able to (sort of) create these:

egen mean = mean(cont), by(cat) egen sd = sd(cont), by(cat) gen upper = mean + sd
gen lower = mean - sd
scatter mean cat || rcap upper lower cat
. . . is the example Nick gave but how would (or could I?) do this for
three different X variables (in Nick's example I suppose it would be 3
different 'cont' variables) on the same graph? I can do this for two but not 3 which brings me to my next problem:
The box plots I created earlier were each side by side for the same
value of X (rather than on top of one another) but the two -rcap- graphs
are on top of each other making it impossible to differentiate the two lines (three would be even worse). Is there a way to separate
these lines or do I need to graph these data in another way altogether?



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