Dear SAS Forum, I have to analyze the data of an experiment where there are four Pools (Boxes filled with water) where there are 2 species of water plants that are subjected or not to a treatment (treatment=adding metals to the water, control=nothing added). Four "parts" (Leave/Stem, Roots, Water near the plant, Soil near the plant) of one plant were analyzed, at each time and in each Pool, for metal concentration (response variable) Sixteen metals are measured on each sub-sample . So 48 sub-samples (4 parts/sample plant) were analyzed. On each of them the concentration of each of the sixteen metals is measured. The design is the following: Pool Species Treat Part Time Id P1 TL C L/S T0 1 P1 TL C R T0 1 P1 TL C Soil T0 1 P1 TL C Water T0 1 P1 TL C L/S T1 2 P1 TL C R T1 2 P1 TL C Soil T1 2 P1 TL C Water T1 2 P1 TL C L/S T2 3 P1 TL C R T2 3 P1 TL C Soil T2 3 P1 TL C Water T2 3 P2 TP C L/S T0 4 P2 TP C R T0 4 P2 TP C Soil T0 4 P2 TP C Water T0 4 P2 TP C L/S T1 5 P2 TP C R T1 5 P2 TP C Soil T1 5 P2 TP C Water T1 5 P2 TP C L/S T2 6 P2 TP C R T2 6 P2 TP C Soil T2 6 P2 TP C Water T2 6 P3 TL M L/S T0 7 P3 TL M R T0 7 P3 TL M Soil T0 7 P3 TL M Water T0 7 P3 TL M L/S T1 8 P3 TL M R T1 8 P3 TL M Soil T1 8 P3 TL M Water T1 8 P3 TL M L/S T2 9 P3 TL M R T2 9 P3 TL M Soil T2 9 P3 TL M Water T2 9 P4 TP M L/S T0 10 P4 TP M R T0 10 P4 TP M Soil T0 10 P4 TP M Water T0 10 P4 TP M L/S T1 11 P4 TP M R T1 11 P4 TP M Soil T1 11 P4 TP M Water T1 11 P4 TP M L/S T2 12 P4 TP M R T2 12 P4 TP M Soil T2 12 P4 TP M Water T2 12 We have repetition through time with pool as the subject and through part with Id (sample plant) as subject. I wonder how to analyze this design to get possibly effects of species, time, treatment and interactions of time and tratment with species . I see that design could not be the best and there are few individuals (Id). I tried the following univariate syntax (the 16 metals analyzed separately). Var is the metal type variable, y is the concentration if the metal. proc mixed data=dati_l; by var; class Var Species Time Pool Treatment Id Part_of_plants; model y= Species Time Treatment Species*Time Species*Treatment /s outp=outp ; repeated Part_of_plants/subject=Id ; random time /subject=Pool s; run; Syntax above worked but for there were random effect calculation or convergence problems. What could be the best syntax for the repeated/random structure of data? Can a multivariate (considering simultaneously all 16 metals analyzed) analysis help? Thank You in advance for helping, Fabio
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