Ray Koopman wrote: > [EMAIL PROTECTED] (Jan) wrote in message > news:<[EMAIL PROTECTED]>... > >>A very basic statistical problem, i fear, but i can't get it solved. I >>have collected data on the occurence of pathology at female ovaries, >>and graded them according to the severity. Left: 1: 91, 2: 31, 3: 7, >>4:3; Right: 1:66, 2:28, 3:6, 4:3; totals: left: 132, right: 103. All >>data are collected on females who present with fertility problems >>(which could case a certain bias). To the best of my knowledge, no-one >>has documented a 50/50 spread between left and right (normally there >>should be no pathology! though some asymptomatic women are probably >>around). Q: 1/Which test should I use to compare left vs right againsi >>grading (if i can due to the difference in spread among grades?!)? >>2/Can I say that left is significantly more affected than right? >>(which test, based on which presumptions)? Thanks a lot!! > > The data should be organized in a 5 by 5 contingency table F in which > F_ij, i,j = 0...4, is the number of women whose left and right ovaries > had severity scores i and j, respectively, where 0 indicates no > pathology. It is not clear what the given values > 1 2 3 4 > L 91 31 7 3 > R 66 28 6 3 > are. Are they the leftmost column F_i0 and the topmost row F_0j, > omitting F_00? Or perhaps the row and column sums, F_i+ and F_+j, > omitting F_0+ and F_+0? > > In any case, the question is about the nature of any asymmetry in F.
I cannot see how this question turns into a contingency table unless the data given are count data. And yet the original question indicated that the numbers represent severity, which to me indicates continuous or ratio scaled data. Even if the data are indeed counts of some type of pathology within an ovary, I can't see how this fits into a contingency table. Thus I would continue to advise that the proper analysis method be a paired t-test if the data are approximately normal, and a nonparameteric Fisher's Sign Test if the data are not approx normal. -- Paige Miller Eastman Kodak Company [EMAIL PROTECTED] http://www.kodak.com "It's nothing until I call it!" -- Bill Klem, NL Umpire "When you get the choice to sit it out or dance, I hope you dance" -- Lee Ann Womack . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
