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Archiver > GENEALOGY-DNA > 2007-02 > 1170703517


From: "Ken Nordtvedt" <>
Subject: Re: [DNA] DYS390m ?
Date: Mon, 5 Feb 2007 12:25:17 -0700
References: <45C7739B.50704@comcast.net>


----- Original Message -----
From: "Bonnie Schrack" <>

>> What the heck is "ascertainment bias"?
>
> Distortion in a dataset caused by the samples or markers used. Or "In
> scientific research, ascertainment bias occurs when false results are
> produced by non-random sampling" (Wikipedia).

For this list I think "... by (or because of) non-random (or biased)
sampling..." would communicate lots better than "ascertainment bias"
>
> Well, that's because none of the people in that dataset were European,
> they were all Asians, therefore there's no contradiction in saying that
> all segments but 390n are invariant in white people.

If mutations on certain segments are showing up routinely in Asians, I'm
sure it is just a matter of sufficient sample size before they will show up
in Europeans.

The so-called "invariance" language used above seems to therefore be with
respect fo a limited sampling? Even if there are less-frequent mutations
in a secondary segments of a STR, it would seem they could serve as
excellent sub-population designators --- sort of like markers with very low
mutation rates.

Ken


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