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RE: Missing values [was: RE: st: simple question]

From   "David E Moore" <[email protected]>
To   [email protected]
Subject   RE: Missing values [was: RE: st: simple question]
Date   Wed, 2 Jun 2004 16:54:35 -0700

Is it worth pointing out that SAS, which may be the most widely used stat
package on the planet, uses missing value codes almost exactly the same way that
Stata uses them.  S-Plus uses an internal code (similar to old-style Stata's
".") and LIMDEP (at least at Version 6.0) used -999 to indicate missing.  While
I too find it sometimes convenient to define arbitrary values as missing in
SPSS, this by no means is a universal approach and has even led to subtle errors
when the missing codes were not properly defined (or handled) as missing.  (Of
course, I never made such errors, but I've heard plenty of stories....)
Nevertheless, I personally prefer the SAS/Stata approach over the SPSS approach.

I also agree that Stat/Transfer should endeavor to preserve unique missing value
codes whenever possible, if it does not do so.

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Richard
> Williams
> Sent: Wednesday, June 02, 2004 2:41 PM
> To: [email protected]
> Subject: Re: Missing values [was: RE: st: simple question]
> At 10:18 PM 6/2/2004 +0100, Nick Cox wrote:
> >Perhaps you could expand on this.
> Sure.  What I dislike is that, unlike other programs, Stata forces you to
> recode the MD values from a data set.  All those 7s, 9s, 99s, etc. will
> have to be recoded to .a, .b, etc.  The values you use for MD will not be
> the same as the values in the published codebooks or that may be reported
> by other users of the data who are using other programs.
> In SPSS, on the other hand, I would just say something like
> Missing Values X (77, 88, 99).
> This isn't a mega problem, but when Stata expanded its possible MD codes
> I'd have rather seen it take an SPSS-type approach than the route it did
> go.  (On the other hand, I suppose you could argue that the rest of the
> world should do things more like Stata.)
> The bigger problem (which is perhaps more of an issue with Stat/Transfer
> than it is with Stata) is that distinctions between types of MD codes get
> lost when converting from SPSS to Stata. I don't know whether this problem
> is unique to Stata or occurs with other types of conversions as well, but I
> would like to see software better address it, e.g. when there are multiple
> MD codes in SPSS assign them to .a, .b, etc. in Stata.
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