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Re: st: -stylerules- updated on SSC
At 04:07 PM 4/13/2005 +0100, Nick Cox wrote:
Some very good rules there Nick. I'd be curious what thoughts people have
about this one:
The package -stylerules- on SSC has been
updated. I started by making a few changes
in the light of Stata 9, but mostly thought
of some other things to mention while
I was doing that.
"Avoid preserve if possible. preserve is attractive to the programmer but
can be expensive in time for the user with large data files. Programmers
should learn to master marksample."
Suppose I ignore that advise and instead do something like
keep if `touse'
1. Will I gain some speed, because Stata will be working with a smaller
data set and won't have to repeatedly process -if `touse'- commands?
2. Isn't there a potential tradeoff between this and another rule, respect
the dataset? If you don't preserve, there is a greater burden on the
programmer to make sure all is well at the end of the run. But, isn't
there also a greater risk if, say, the user stops the program before
I suppose good, careful programmers can guarantee both speed and security
of data. But, I would add the caveat that, if you are not 100% confident
of your programming, you might want to favor safety over speed.
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