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Re: st: Problem with seed and bootstrap
At 11:45 AM -0500 9/19/05, Richard Williams wrote:
I think what is most troubling about -unstable- is that its results
can't be reproduced; you can run the exact same problem twice and
get different sort orders.
If -unstable- produced reproducible outcomes i think people would
feel more comfortable with it.
Reproducibility is indeed the issue here, but it is the use of the
-stable- option (more precisely, the reliance on it) that can lead to
a result not being reproducible. If -sort- can yield different
outcomes (i.e., if the variable(s) you are sorting on does not
uniquely identify the observations) *and* if the result(s) you are
producing can be affected by this, then that is a programming bug.
You may get lucky using -stable-, but in a sense that just moves the
problem upstream and makes it less clear to someone reading the code
what is going on. Moreover, you have substantially increased the
likelihood that future changes to the code will cause problems.
If you are doing something which is dependent upon a certain ordering
of the data, then that ordering should be completely and
unambiguously specified beforehand. And the use of -sort- (i.e., the
unstable version) with sufficient variables to establish that order
is the easiest and most concise way of doing that.
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