st: Strange interaction between weights and the -mlabel()- option

[Roger Newson <roger.newson@kcl.ac.uk>]

Fellow Statalisters (especially StataCorp):

I am currently using Stata 8.2 under Windows 2000, with executable and 
ado-files dated 06 Oct 2004, which is the latest available version 
according to -update query-. I have discovered what appears to be a strange 
interaction between weights and the -mlabel()- option of the -scatter-, 
-connected- and -dropline- plot subcommands of -graph twoway-. The weights 
seem to be ignored if -mlabel()- is specified. For instance, in the -auto- 
data, if I type

. twoway scatter mpg weight [awei=price]

then, as expected, -mpg- is plotted against -weight-, with symbols 
unlabelled and weighted by -price-. And, if I type


. twoway scatter mpg weight, mlab(make)

then, as expected, -mpg- is plotted against -weight-, with symbols 
unweighted and labelled by -make-. However, if I type

. twoway scatter mpg weight [awei=price], mlab(make)

then -mpg- is plotted against -weight-, and the symbols are labelled by 
-make-, but are unweighted. The same interaction is observed if I use 
-pweights- and -fweights- instead of -aweights-, and if I use -twoway 
connected- or -twoway dropline- instead of -twoway scatter-.

Is this interaction intentional or a bug? And does it have any connection 
to the similar strange interaction between weights and the -connect()- 
option which I discovered earlier (and which was fixed in the update of 05 
Oct 2004 - thanks again to StataCorp for that)? I can find no mention of it 
in -[G] graph twoway scatter-. However, I realise that, if the symbols are 
weighted, then there may possibly be a problem deciding the default value 
for the -mlabgap()- option.

Best wishes (and thanks in advance)

Roger


--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
5th Floor, Capital House
42 Weston Street
London SE1 3QD
United Kingdom

Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
  or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://www.kcl-phs.org.uk/rogernewson

Opinions expressed are those of the author, not the institution.

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