-catplot- from SSC does this.

sysuse auto, clear

catplot foreign rep78

Hillel's analogue would be something like

catplot gender classroom

The main trick behind -catplot- is precisely that explained by Phil Clayton, although there are other tricks too, including handles for percent calculations. There was some discussion within

SJ-4-2 gr0004 . Speaking Stata: Graphing categorical and compositional data

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox

Q2/04 SJ 4(2):190--215 (no commands)

discusses graphical possibilities for categorical and

compositional data

(although please note that the syntax was changed in -catplot- 2.0.0 from SSC),

and there are examples at

http://www.ats.ucla.edu/stat/stata/faq/graph/njcplot.htmNick

[hidden email]
P.S. Sergiy's example is strictly not a histogram, but a bar chart showing means.

Phil Clayton

============

Sometimes I generate a "dummy" frequency variable equal to 1 in order to generate a frequency plot:

gen byte freq=1

graph bar (sum) freq, over(sex) over(classroom) asyvars

David Radwin

============

I'm not sure if this is what you mean, but you might try -bihist- for two groups and -byhist- for more than two groups. Both programs are written by Austin Nichols and available from SSC.

Sergiy Radyakin

===============

Try the following example:

sysuse auto, clear

graph bar turn gear_ratio, over(rep78)

in your data replace "turn" with boys, "gear_ratio" with girls and "rep78" with classroom.

Refer to M.Mitchell's book for graphical questions:

http://books.google.com/books?id=D0aYj9TDjdEC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=falseSee section 5.2 in particular.

Hillel Alpert

==============

Could anyone advise if Stata can be used to generate a histogram showing multiple bars per category of the variable being plotted? Each bar would be the frequency or percentage of the variable for a subcategory of a second variable.

For example, the histogram would show the numbers of boys and girls in each of ten classrooms, where the bars for boys and girls of each classroom are adjacent to one another.

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