Figure : A comparison of the SEM estimated by MBAR from one replica and then averaged over 5 replicas, compared to a "TIES-like" error calculated by computing SEM of the bootstrapping result of 5 replicas. Panels a) and b) show the results for the ligand-protein and ligand only simulations respectively. The x-axis denotes an index assigned to each ligand transformation. This index runs from zero to the total number of transformations minus one, within each protein target across all engines.