I'm with Allan on this. Implementing "if x>y" to evaluate
as True when x is missing is a logical flaw and should be
corrected. After 10+ years with Stata, I still occasionally
fall into this trap. I figure that if I can deal with -index()-
being changed to... now what was it?... I can deal with a
real flaw being fixed!
-----------------------------------
Thomas J. Steichen
[email protected]
-----------------------------------
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Allan Reese (Cefas)
Sent: Tuesday, January 08, 2008 6:03 AM
To: [email protected]
Subject: st: RE: statalist-digest V4 #2935 - strange world
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".
It's indeed a strange world where the priests of IT can claim "user error" when you fall into a trap they set. Software will at some time come under the remit of health and safety legislation - IT's doin' me 'ed in!
Allan
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