Ali wrote:
I need to see the effect of a binary exposure variable on the distribution of
birthweight. I expect that there is a shift in the ditribution and want to show
this shift by producing a histogram which shows the distribution of exposed and
unexposed seperately but on the same plot. Is there a code that can do this in
Stata?
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To be precise: I think you ask for two PLOTS (histograms) on the same GRAPH,
i.e. in the same coordinate system. Let's use the auto dataset, although it
is about carweights, not babyweights.
Friedrichs suggestion:
sysuse auto , clear
histogram weight , by(foreign)
I don't think that is what you wanted, but we may come closer by putting the
two graphs in one column:
histogram weight , by(foreign , col(1))
I would improve it, (1) by removing a rather useless note, (2) by controlling
the bins, and (3) by displaying frequency rather than density:
histogram weight , frequency start(1500) width(500) by(foreign , col(1) note(""))
If you really want the two groups within the same coordinate system, I don't
see how -histogram- can do it, but we can make -graph bar- do this:
egen weightgr = cut(weight) , at(1500(500)5000)
generate x=1
graph bar (sum) x , over(foreign) over(weightgr) asyvars
I don't think it is better than the histogram solution. But there is another
good solution with -dotplot- (it is described in the [R] manual):
dotplot weight , over(foreign) center
Hope this helps
Svend
________________________________________________________
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000 Aarhus C, Denmark
Phone, work: +45 8942 6090
Phone, home: +45 8693 7796
Fax: +45 8613 1580
E-mail: [email protected]
_________________________________________________________
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