The utilized dataset was investigated for 119 compounds in a previous report . In this dataset in addition to the compound's name, Kp values in each tissue and several properties described in "Properties for explanatory variables" below were included. The amount of data differed for each tissue (adipose, 69; bone,42; brain,89; gut,66; heart,94; kidney,92; liver,85; lung,93; muscle,104; skin,64; and spleen,34). Because the amount of bone and spleen data was significantly small, we decided to omit these tissues.