At 04:18 PM 5/4/99 +0000, [log in to unmask] wrote:
>Can anyone point me to a useful reference for estimating a confidence
>interval for the mean of a moderate (60+) number of observations for which
>values 0, 2,3,4,5,6,7,8 are possible. I have several observed average
>values for different conditions, and need to check whether they are
>significantly different from one another or from a global mean.
Have you looked at the jackknife or bootstrap? Or is
the power loss too much for you there?
--jt
>
>Background:
>A colleague has carried out an experiment in which she counted the
>number of matching DNA profiles found after amplification using standard
>heating blocks. After doing the experiment (*&%!*) she came to find out
>what constituted a significant result.
>
>She ran 8 profiles per run, spread (consistently) between three different
>positions. The possible number of matches is 0, 2,3,4,5,6,7,8. (ie it doesn't
>include 1). She now has average values for each position, and for the
>average number of matches per run.
>
>It may help to know that the match rate is quite high, so zero is a
relatively
>rare occurrence - c. 5%
>
>BTW: there are only 3 distinct types of position on the blocks; a
>chi-squared test on observed avergae for each against expected global
>average is woefully insensitive with only 2df. I'm looking for something that
>is sensitive to the number of runs, which is of the order of 60 runs, or 480
>separate observations.
>
>------------------------------------
>Steve Ellison
>Laboratory of the Government Chemist
>Queens Road, Teddington, Middlesex
>ENGLAND TW11 0LY
>
>Phone: [ +44 | 0 ]181-943-7325
>Fax: [ +44 | 0 ]181-943-2767
>
>
________________________________________________________________
Jan Theodore Galkowski :=°o°:- (:-)}
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