Quantitative structure-property relationships in group 4 metallocene olefin polymerization catalysts were constructed for a dataset of 8 zirconocenes in a combined experimental and quantum chemical study. A total of 45 descriptors measuring the steric and electronic influence of the rac-SiMe2[Ind](2) based ligand framework were correlated with the observed polymerization activities, together with the molecular weights, melting temperatures, stereoerrors and regioerrors of the produced isotactic polypropene. Direct correlations between the calculated descriptors and observed catalytic properties turned out to be relatively weak due to the combined steric and electronic effects of multiple descriptors. Multiple regression models based on ordinary least squares linear regression and principal component regression techniques typically led to significant improvements, particularly for the molecular weights, melting temperatures and regioerrors, providing R-2 of up to 0.92. The results provide a solid starting point for an extension of the methodology for a greater variety of catalyst structures, and thereby for the development of new high-performance catalysts for this industrially important process. (C) 2015 Elsevier B.V. All rights reserved.