Sources of dataset variance. (A) Cluster dendrogram of average linkage showing similarities between assays and tissue types. Samples tended to cluster by assay type (IVT/DASL) and preservation style (Frozen/Fixed). (B) To quantify the effects of these predictors on the variance in the dataset, MDMR analysis was conducted. Single and multiple regression MDMR analysis are shown. Assay (IVT/DASL), source (Frozen/Fixed), batch, diagnosis, age, and gender of case from which tissue samples were taken were assessed. In the single regression model, each predictor is assessed separately; in the multiple regression model, each predictor is tested in relation with the other predictors in the model, yielding a cumulative percent variance explained (PVE).