# st: Multiple (overlaid) Histogram

 From "J. Michael Oakes" <[email protected]> To Statalist <[email protected]> Subject st: Multiple (overlaid) Histogram Date Wed, 28 May 2003 09:42:43 -0500

```Using Stata 8, I want to produce a single histogram for MULTIPLE x-point
Likert-scale variables Y1 Y2... Yn (n << 5 for clarity). That is, I'd like
to compare discrete distributions side by side with something like this
(hopefully not mangled example) for two variables Y1 and Y2 over a 3+ point
Likert scale...

|
|	         ______
|	         |    |	        ______
p  |	         |	  |	        |	 |
e  |      ______ |    |           |	 |
r  |      |    | |    |           |    |
c  |      |    | |    |           |    |
e  | _____| Y2 | |    |      _____| Y2 |
n  | |    |    | |    |_____ |    |    |
t  | | Y1 |    | | Y1 |    | | Y1 |    |
| |    |    | |    | Y2 | |    |    |
| |    |    | |    |    | |    |    |
-----+-------------+-----------+---------->>
1		  2             3

My data is a conventional structure where respondents are indexed by rows
and outcome variables are in columns, such as:

_n	 Y1     Y2
-----   ----  -----
1	 1     2
2	 2     1
3      1     3
.      .     .

Given such data, my sense is that the desired graph is technically two
histograms overlaid (like in <twoway>) on each other. But since <histogram>
is not a <twoway> plot such a histogram is not possible: currently
<histogram> can only plot one variable at a time (I think).

While I can imagine transforming my data through some complicated collapse
and append commands, and then using <twoway bar>, this is simply too much
work. Relatedly, I could use Excel and other such programs to produce the
plot easily with summarized data. But I really want to avoid dumping data to
another program, especially Excel.

Am I again missing something, or does <histogram> need some improvement?

Thanks in Advance - Michael Oakes

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