A key result from table 1 is that there is no statistically significant difference between the calculated properties for TI and FEP results in all cases. In order to make the comparison between FEP and TI more rigorously, the calculated ∆∆Gs for each ligand transformations ing significantly different TI and FEP results. All differences are found for the thrombin target when using the NAMD methods. The OpenMM implementation had no statistically significant differences for any protein targets. In the NAMD2 case the significantly different transformations are l1-l8 and l2-l5 and in the NAMD3 case these are l8-l1, l1-l4 and l2-l5.