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Re: st: My last word on strange world

From   Jeph Herrin <[email protected]>
To   [email protected]
Subject   Re: st: My last word on strange world
Date   Thu, 10 Jan 2008 11:56:06 -0500

Nick Cox wrote:
> NJC>>> Are you asking that 42 > . and 42 < . _both_ return FALSE? 

Yep. Missing means empty set, and you can't compare a real
number to the empty set. 42 is neither larger nor smaller than
the elements of the empty set, so these return FALSE.

> That . == . returns FALSE? 

No, the empty set equals itself. This should return TRUE.

> If a user sorts on a variable which has missing values, then
> Stata could return an error message saying that the variable
> cannot be sorted because of missing values. The user can then
> repair or truncate their data so that sorting makes sense.
> NJC >>> Sorry, but I think that's the most impracticable suggestion 
> so far in this thread, with some stiff competition! 

I disagree. Replacing missings with -99 or 10E23 is a perfectly
practical, not to mention well-tested, approach. I like knowing
when data is missing, but if I want to treat missing as a number
it should be up to me how I choose to do so.


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