st: qplot , over()

[Keith Dear <keithdear4@gmail.com>]

How can I get several quantile plots in one diagram?
(There have been past threads on this, but I found no mention of what
I am getting.)

sysuse auto
replace mpg=mpg/2 if foreign   // for greater separation
qplot mpg, by(foreign)      // two distinct curves, which I would like
to plot together
qplot mpg, over(foreign)  // points on a single curve, not what I expected

Am I misunderstanding the help file? It seems to imply that by() and
over() give the same set of curves, which is what I want but isn't
what happens:

---- help qplot
by(varname[, suboptions]) specifies that calculations be carried out
separately for each distinct value of a
        specified single variable. Results will be shown separately in
distinct panels. See [G] by_option.
over(varname) specifies that calculations be carried out separately
for each distinct value of a specified
        single variable.  Curves will be shown together within the
same panel.  over() is only allowed with a single
        varname.
----

-qplot- is by NJC out of -net install gr42_5.pkg-


-- 
Dr Keith Dear
National Centre for Epidemiology and Population Health
ANU College of Medicine, Biology and Environment
Australian National University
Canberra, ACT 0200 Australia
Phone +61 (02) 6273 2208
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