On 3 Dec 2003 04:41:09 -0800, [EMAIL PROTECTED] (Karl) wrote: > Hallo! > > I have data of the following design: > N subjects were measured at Baseline (visit 1) and at 3 following time > points (visit 2-4). There is or is not a treatment. Say, the results > of visits 1 to 4 are Y1, Y2, Y3, Y4. > > T: Variable Treatment (yes/no) > V: Variable Visit (2, 3, 4 - without baseline) > id: Variable subject identification number > N: number of subjects > > Most interesting is the question if there is a difference in treatment > between the results of visit 4 and baseline. (The other time points > are also of interest.) >
The MANOVA suggested by Jim Clark sounds like good advice to me, given the absence of warning signs. Is change expected in both groups? - Are equal changes expected in each time period, or would more change be expected early? - early change could justify using the average of three followups as the main criterion. How serious are you about the single end-point at visit 4? - that suggests a simpler design, where you compare the treatments at 4 while using 1 as a covariate. For any design, it will be useful to confirm that there were no initial differences, despite randomization of the treatment condition. Of course, the equal-start is more critical if subjects were not randomized. -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html "Taxes are the price we pay for civilization." . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
