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Re: st: My last word on strange world

From   Richard Williams <[email protected]>
To   [email protected], [email protected]
Subject   Re: st: My last word on strange world
Date   Fri, 11 Jan 2008 12:08:34 -0500

At 11:35 AM 1/11/2008, William Gould, StataCorp LP wrote:
It therefore follows

     x>=100      evaluates to false if x is missing

and thus the statements (x>=100) and (x<100) are both false and, as I asked
about Jeph's comment, is that really in line with the expectations of
ordinary users?
It is with mine. To me, missing is not a number, large or small. And, because of that, in practice the coding is usually more like

x > = 100 & !missing(x)

which I find awkward and mistake prone. My own preference would therefore be that the statements be more like


One and only one of the above three would be true. This also makes it explicit that how to handle missing is a separate decision.

There are going to be gotchas with any system. I therefore think that the default should be whatever people are likely to want most frequently. And I think it is relatively rare that when you have a statement like


that people intend for missing to be evaluated as true. If they do, that is when they can go to the extra work and code

x>=100 | missing(x)

Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
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