|
|  |
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
Re: st: Drawing histograms
On 26 Ean 2007, at 03:04, Lucy @ Mac wrote:
I'd like to graph two categorical variables in one histogram to
compared
var1 to var2. What's the best way to do that?
Stata doesn't let you interact with histograms to change the bin
width and start values, but packages that do (JMP for instance) can
be used to give a scary demonstration. There is a large number of
different-looking histograms that can be generated from the same
dataset.
When comparing two histograms, there are a number of visual problems
1. Any histogram is a complex shape. Try looking at one and then
drawing it from memory. It's difficult. So being able to compare two
histograms is hindered by the brain's difficulty seeing a histogram
as a whole.
2. Because many different-looking histograms can be drawn from the
same data, it is hard to say which differences between a pair of
histograms are due to differences in the data and which reflect the
vicissitudes of bin width and startpoints.
3. The meaning of the differences observed between two histograms is
unclear.
I would try dotplots, with these options
. sysuse auto
. dotplot mpg, over(foreign) median bar cent
=========
Ron�n Conroy
Royal College of Surgeons in Ireland
[email protected]
+353 (0) 1 402 2431
+353 (0) 87 799 97 95
http://www.flickr.com/photos/ronanconroy
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
