In article <19970414173000.NAA22228 at ladder01.news.aol.com> jlk1117440 at aol.com (Jlk1117440) writes:
In article <19970414173000.NAA22228 at ladder01.news.aol.com> jlk1117440 at aol.com (Jlk1117440) writes:
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>From: jlk1117440 at aol.com (Jlk1117440)
>Newsgroups: bionet.immunology
>Subject: ELISA question
>Date: 14 Apr 1997 17:31:02 GMT
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>I have performed an ELISA to detect patients' reactivity with a naturally
>occuring protein (about 28 kDa). Now I have optical density readings of
>the plate, but am not sure if the numbers are significant. For example,
>if one patient's reading is .250 and another's is .050, is the former
>positive and the latter negative? I would appreciate any help.
>Jim Knoetgen, MD
>St. Luke's - Roosevelt Hospital Center
>New York, New York
Jim:
Run the tests in quadruplicate and compare the negative samples with the
problem samples by the Mann-Whitney-Wilcoxon (or Wilcoxon rank-sum) test if
they are independent, or the Wilcoxon signed-rank test if they are related.
If you get a statistical significance of the difference of 0.05 or smaller,
you have a solid basis to say that the negative and the problem samples are
different. See Barriga et al, J. Parasitol., 77:703-709, 1991.
Good luck,
Omar O.Barriga, DVM, PhD