Analyzing over-represented parameters in the outliers of TFD helps better understand errors in torsion fitting, since torsions are applied in diverse chemical contexts and sometimes a group of torsions can pass through the same central bond. Improper torsion parameters have also not yet been optimized, providing further opportunity to improve the force field in subsequent work, as some of the parameters describe improper angles with errors as high as 60 • compared to QM. Whether improper torsion scans are needed, or using current data in the form of proper torsion scans and optimized geometries will suffice is a question to be answered.