All regression results for each of the 6,929 data of cation intercalant and base-like host and 168 data of anion and acidlike host are presented in Figures ) and (b), respectively. Both plots display the R 2 and MAE for the entire model calculated from all predicted values in eq. 4, confirming the validity of the regression equation with high linearity. In other words, in layered intercalation compounds, as in complex compounds, the compatibility between host and intercalant can be understood by considering HSAB interactions and size effects (Coulombic interactions).