[EMAIL PROTECTED] (Jay Warner) wrote: >Try this: >When a measurement in group A is linked specifically to a >measurement in group B, we can discuss paired measurements. > >Examples: >Two different paints are compared, by painting them on the same >substrate sample, half of each substrate for each paint. Now, >differences in paint performance due to substrate prep will cancel >out, and we can more easily see differences due to paint source. > >Differences in opinion due to female and male sources: We query >married couples seperately, and get their opinions on lots of >subjects, using a Likert scale (!). Then we see if the differences >between gender, _within_ a married couple, are much different. > >Does one test sample (such as a TB test) produce a larger >response than a different type of test material? We apply test 1 to >one side of the patients, and test 2 to the other side. Do we see >differences in response, _on the same patient_? > >In each case there is a linkage, a commonality, for each >measurement in the two groups. By using a paired t test, we >reduce the variance, and have a mosre sensitive test.
Thanks for the clear and illustrative examples. Peter . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
