I am interested to test the effects of 4 rates of organic matter (OM) on soil compaction at 2 soil depths over 6 time periods (every 3 months for 2 years).
I will divide an experimental field into 12 sections where every 3 sections (selected randomly) will receive the same OM rate. This means for every OM rate, there will be 3 replicates (i.e., 3 reps x 4 OM rates = 12 sections/plots). The soil compaction at 2 soil depths, in every section, will be measured repeatedly for 6 times. My suggested exp. design is a three-factor 4x2x6 factorial design with repeated measures on the last 2 factors (soil depth and time). In other words, this is a one between- (OM rates) and two within-subjects (soil depths and time) design. The reason I am treating the soil depth factor as a within-subject factor is that any effects on soil properties in two soil depths tend to be correlated. This means if OM affects soil compaction in one soil depth in one way, it will also tend to affect the other soil depth in the same way (albeit in a smaller degree). This is because soil properties from two soil depths have similar (but not equivalent) properties, so they both tend to be correlated. Please advise. Thank you for the time and trouble. Regards, Chris. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
