| From: | David Fetter <david(at)fetter(dot)org> |
|---|---|
| To: | Michael Dean <mdean(at)sourceview(dot)com> |
| Cc: | Greg Stark <gsstark(at)mit(dot)edu>, josh(at)agliodbs(dot)com, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: More thoughts about planner's cost estimates |
| Date: | 2006-06-02 20:56:11 |
| Message-ID: | 20060602205611.GA23684@fetter.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Fri, Jun 02, 2006 at 01:39:32PM -0700, Michael Dean wrote:
> I'm sorry to interrupt your esoteric (to me) discussion, but I have
> a very simple question: would you define a "good unbiased sample"?
> My statistics professor Dan Price (rest his soul) would tell me
> there are only random samples of some sort, and "other", which are
> always biased, and never good.
What's at issue here is a biased estimator, not a biased sample. If
you know an unbiased estimator of multiplicity based on a random
sample, that would be a great :)
Cheers,
D
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
phone: +1 415 235 3778 AIM: dfetter666
Skype: davidfetter
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