RE: [S] Possible Statistical Enhancements to S-PLUS

Mark Bravington FSMG CEFAS (M.V.BRAVINGTON@cefas.co.uk)
Mon, 30 Mar 1998 14:50:31 +0100


fao Charles Roosen--

THESE ARE A FEW OF MY FAVOURITE THINGS:

In fitting GAMs:

(1) the ability to have independent smooths in different factor levels. EG
growth~ lo( temperature) %in% gender

(2) cyclic smoothers, e.g. depth~lo( julian.date, period=365). The "supsmu" function can already do this (but not in GAMs), and
there's absolutely no reason why "lo" and "s" couldn't be adapted. Although one can fudge a result via
depth~lo( sin( 2*julian.date %% 365)) + lo( cos( 2*pi*julian.date %% 365)), this is less satisfactory for several reasons, e.g. how to interpret degrees-of-freedom.

In "survreg":
(3) the ability to handle negative responses without complaint. This behaviour could be governed by a
parameter "allow.negative=F" in the arguments, for consistency with the current version. I have used "survreg" to
analyze censored non-survival data (at the suggestion of s-news; I hadn't realized it was useful outside
survival analysis) and it was awkward to have to adjust my data to fit the program's requirements.

Unlike other respondents, I have had no problems linking external code to S-PLUS (in my case, DLLs written in Delphi); it's easy and incredibly useful. But I appreciate that things are not so straightforward on other platforms.

Thanks for asking--

Mark Bravington
m.v.bravington@cefas.co.uk
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