Dear Nick:
As always, very useful.
Thank s a lot.
José Maria
Jose Maria Pacheco de Souza, Professor Titular (aposentado)
Departamento de Epidemiologia/Faculdade de Saude Publica, USP
Av. Dr. Arnaldo, 715
01246-904 - S. Paulo/SP - Brasil
fones (11)3061-7747; (11)3768-8612;(11)3714-2403
www.fsp.usp.br/~jmpsouza
----- Original Message -----
From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Wednesday, October 14, 2009 11:37 AM
Subject: st: RE: Re: -pieplot- available from SSC
The question of radar or spider plots has arisen before. Typing
. findit radar
would have pointed you to Adrian Mander's -radar- on SSC. Two generic
problems for radar or spider graphs are comparing values that are not
close by and comparing with numeric scales, which are usually only tacit.
Various graphs for circular data are included in -circular- on SSC.
Although set up for data measured in degrees, they are applicable to some
extent to data on other circular scales. I gave a talk on this package at
the London users' meeting in September.
I don't agree that data that are seasonal (diurnal, etc.) are usually
better plotted in circular diagrams. In fact 80 or 90 years ago, Brinton
and Karsten were scathing about such graphs in their compendia, e.g.
Karsten, K. 1923. Graphs and charts. New York: Prentice-Hall, p.237 "When
the clock-chart has been well and carefully drawn, it is ready for the
waste-basket."
Karsten is perhaps more widely remembered for having had the basic idea of
a hedge fund; these days that may not seem much of an honour.
For more constructive suggestions on plotting seasonal data -- adaptable
to other cycles -- see
SJ-9-2 gr0037 . . . . . . . . Stata tip 76: Separating seasonal time
series
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J.
Cox
Q2/09 SJ 9(2):321--326 (no
commands)
tip on separating seasonal time series
SJ-6-3 gr0025 . . . . . . . . . . . . Speaking Stata: Graphs for all
seasons
(help cycleplot, sliceplot if installed) . . . . . . . . . N. J.
Cox
Q3/06 SJ 6(3):397--419
illustrates producing graphs showing time-series seasonality
The earlier of these papers is accessible to all in .pdf form on the Stata
Journal website, as it came out just over three years ago. It's one of the
Speaking Stata columns I'm most fond of.
Nick
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