AFAIK, Partition coefficient is A2 material [Chromatography, ugh!] And thus will not be coming in tomorrows paper. Besides that, I'd rather have refreshed it in my mind before relating it to you, but in summary, it is the degree to which something gives preference to one solvent over another. The greater its partition coeffecient in a particular medium, the greater its likelihood to dissolve within it and either move forward if the solvent happens to be the mobile phase, or stick in the a static position if the solvent was the stationary phase. It measures the CONCENTRATION of the SOLUTE in each solvent and forms an equation relating the two in a RATIO method. Kind of like Asking a group of people if they prefer PMLN or PTI and making a survey out of it