High intra- and inter-plate reproducibility in treatment-related effects. (A) Intra-plate reproducibility (replicate treatment wells on the same plate) across all donors following treatment with control compounds isoproterenol (10 μM), propranolol (0.5 μM), and cisapride (0.1 μM), for the chemical-specific phenotype of interest. Pearson (r) and Spearman (ρ) correlation coefficients are shown in the upper left corner of each graph. (B) Inter-plate reproducibility (corresponding wells on replicate plates for the same donor, concentration, and cardiotoxicity parameter) following treatment with test chemicals for four main phenotypes, across 13 donors with replicate plates. Pearson (r) and Spearman (ρ) correlation coefficients are shown. (C) Inter-plate reproducibility following treatment with test chemicals for the phenotype beats per minute (BPM), shown individually for each donor with replicate plates. Pearson (r) correlation coefficients are shown. (D) Inter-batch reproducibility (all pairwise comparisons across 8 batches of the standard donor ID 1434), summarized by Pearson correlation coefficients, for all 9 phenotypes.