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...s a month apart for duplicate analysis. The response is the concentration of (unspecified) analyte in g/kg". I understand what is written in the book about the linear mixed model (nested). Laboratories and batches are treated as random and to assess components of variation. However, I have an extral question about it. From the analysis, we can evaluate the variance from different labs. Let's say a training program was done to the labs, I want to see whether after the trainning program, the variance from the lab (sigma_L in the book) becomes smaller or not. Basically I need to compare \sigm...