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

[Steven Dubnoff <sdubnoff@circlesys.com>]

> 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.

We considered doing this when we added support for extended (a-z) missing 
value codes in SAS and Stata.  The problem is complicated by fact that SPSS 
user missing values have no inherent meaning.  All that we can do is assign 
the first missing value for a variable to .a and the second to .b, and so 
on.  Which numeric values get assigned to each extended missing value will 
depend on the order in which they were defined in SPSS, which may or may 
not be known to the user.

Nonetheless, this feature has been requested often enough that it will put 
in the next version as an extension to our missing value handling option 
(all,first,none).  A fourth option "extended" will map values, in the order 
defined in SPSS to .a, .b and .c.

If any users have any ideas for handling this in a more elegant manner, 
please contact me off list.

Best,

Steve




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Steven Dubnoff              sdubnoff@circlesys.com
Circle Systems              We make your data instantly usable.
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