To close this thread, here is a solution to my problem that was
provided by Stata tech support. One has to duplicate the observations
and recode the group variable in the duplicates so that the weights
are distributed across all groups.
. clear all
. input x y weight group
1 1 1 1
2 1 2 1
1 2 4 2
2 2 8 2
end
. scatter y x [w=weight], name(A)
. twoway (scatter y x if group==1 [w=weight]) (scatter y x if group==2
[w=weight]), name(B) legend(off)
. expand 2
. replace x = . if _n>(_N/2)
. recode group (1=2) (2=1) if x==.
. twoway (scatter y x if group==1 [w=weight]) (scatter y x if group==2
[w=weight]), name(C) legend(off)
The legend is turned off so that it is easier to see that the markers
in graphs A and C have the same size. A more complicated example is
shown in a reply to a similar question by another list member.
http://www.stata.com/statalist/archive/2008-08/msg00982.html
Friedrich
On Tue, Jul 29, 2008 at 7:36 PM, Friedrich Huebler <[email protected]> wrote:
> -scatter- supports weights. When a scatterplot is drawn, all weighted
> markers have a distinct size. This size changes when the data are
> divided into two or more groups and then drawn as overlaid
> scatterplots. I am looking for a way to retain the size of the
> original markers. The problem is best understood with an example.
>
> clear all
> input x y weight group
> 1 1 1 1
> 2 1 10 1
> 1 2 100 2
> 2 2 1000 2
> end
> scatter y x [w=weight], name(A)
> twoway (scatter y x if group==1 [w=weight]) ///
> (scatter y x if group==2 [w=weight]), name(B)
>
> Compare graphs A and B. In graph A all four markers have a different
> size. In graph B there are two pairs of markers with the same size. I
> would like to have the same marker sizes in graph B as in graph A
> while keeping the colors that identify the two different groups. How
> can I do this?
>
> Thanks,
>
> Friedrich
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