Jan wrote: > 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!!
If the severity are normally distributed, you can use a paired t-test. Do not use the two-sample t-test. If the severity are not normally distributed, you might consider a non-parametric test such as Fisher's Sign Test. -- 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/ . =================================================================
