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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°:- (:-)} **************************************************************** FAX 630-214-8625 E-mail at work :- [log in to unmask] Personal e-mail :- [log in to unmask] Personal e-mail :- [log in to unmask] Personal e-mail :- [log in to unmask] **************************************************************** http://home.att.net/~jtgalkowski/algebraist.htm **************************************************************** Seek simplicity[,] and distrust it. --A. N. Whitehead **************************************************************** %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%