I am not sure if I use the right model for my data, can anyone help me to take a look at it? The experiment is to evaluate the impact of different spray timing of a fungicide on leaf spot disease of barley. Here is the experimental design: 2 location, 2 seeding dates, 5 spray timings including control, 4 replications, 3 cultivars; variables include disease severity (%), and yield. Here is the code I wrote: proc glimmix data=all; class loc sd rep spd cv; model ds=loc|sd|cv|spd/dist=normal link=identity; random rep; random _residual_/subject=loc*sd*spd*cv type=ar(1); lsmeans loc*sd loc*cv loc*spd spd*cv/diff lines; run; I am just start to learn sas by myself, have a lot of questions. 1. how to determine a data distribution; 2. how to determine random effect co variance structure? Thanks for the help.
... View more