Apart from the correlation, it is often more useful to calculate mean absolute error (MAE) for each comparison (Table ). It shows that the closest pair of methods are both cell-based methods (CACO-2 and MDCK) followed by their pairs with their membrane-based counterpart sharing similar rangeapparent PAMPA. The error between BLM and both computational methods is comparable to the MAE in between them, but their similarity to cell-based methods is weak with the largest error. As a negative control, we have tried mean predictor, i.e. we calculated MAE of each method towards the mean average value calculated on its dataset. This value serves as a negative control for the fit to that dataset. If the MAE value for pair is lower or at least similar than MAE to mean predictor, then it can be combined. This comparison has shown that we can combine both cell-based methods (CACO-2 and MDCK) together with apparent PAMPA. Similarly, both computed physics-based methods (COSMOperm and PerMM) can be used to predict membrane-based BLM method and to some extent also to intrinsic PAMPA.