It's often useful to compare histograms for some key variable, stratified by levels of some other variable. There are several ways to display something like this. The simplest may be to plot the two histograms in separate panels.

**SAS**

In SAS, the most direct and generalizable approach is through the

`sgpanel`procedure.

proc sgpanel data = 'c:\book\help.sas7bdat';

panelby female;

histogram cesd;

run;

The results are shown above.

**R**

In R, the

`lattice`package provides a similarly direct approach.

ds = read.csv("http://www.math.smith.edu/r/data/help.csv")

ds$gender = ifelse(ds$female==1, "female", "male")

library(lattice)

histogram(~ cesd | gender, data=ds)

The results are shown below.

## 3 comments:

Does the Side-by-side histogram at the top of the page have any copyrights on it?

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For SAS.....If the 'female field' were continuous (say 1-10), how would you specify bin increments for each lattice graph in SAS? In R, one would enter the increment in the histogram statement - not sure about SAS

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