Nick--
As usual, I agree with most of your points, but Allan raises a
different objection--he does not want Stata to stop treating (.) as
more than any finite number, or (.a) as more than (.), but only to
report that it is doing so when a calculation or comparison involves
missing values. I think that warning messages are a very good idea,
while changing Stata's logic is a very bad one. This behavior of
missing values seems to confuse enough people to justify a (small) set
of warnings for these kinds of cases. The trouble is, the warning
message would have to trap every -if- qualifier on every command,
which sounds like it could involve a lot of work. Maybe just
-generate- and -replace- would be a good start? In that case, you
would also want a warning message for a statement like
. gen hirep=rep78>3
On Jan 8, 2008 11:39 AM, Nick Cox <[email protected]> wrote:
> I am with StataCorp on this, not that they need my
> support.
<snip>
> Allan Reese
> ===========
>
> Others have pointed out that "if x>y" in Stata evaluates as True when x
> is missing "."
>
> I've raised this before and had to accept as a feature of Stata that "."
> is a big number and "computers do what you tell them, not what you
> want." Nevertheless, I remain of the opinion that it is
> counter-intuitive, logically incorrect, and undoubtedly leads to
> computer-assisted errors. Changing the operation of Stata now would
> inconvenience most current users, but it would not be inconsistent if
> the kernel were adapted to output a warning after such calculations
> "Missing values included - check your results".
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