Hello all, First of all, I am pretty new to mixed model but to analyze an experiment, I need help to understand what I am doing. Thanks in advance. My data set is the following: 130 groups (suspc.) in which 4 random samples within the group are analyzed for 2 consecutive year (the 4 samples the following year are chosen at random as well, not the same as the previous year) (8 samples per group in total). These sample are analyzed to get the concentration of 2 components, A and B. The data set is unbalanced: data on concentration of A and/or B may be missing for some samples. Thus, random var=(sample within the group) ; fixed var=(group), (component), (year) ; y=(concentration) Then, I want to analyze which groups have a greater concentration of A and B and if the year has a significance importance. I also want to see if there is a significant correlation between the concentration of A and B in general (not for every single group). So I don't really know where to start other than building my data set in long form and trying to run a PROC MIXED. I am relatively new to SAS and mixed models. Thank you very much guys, Gabriel, Undergrad Student in ChemE
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