1. A system configured to generate a defect sample for electron beam review, comprising: an optical inspection subsystem configured to detect defects on a wafer; an optical review subsystem configured to review defects detected on the wafer the optical inspection subsystem; an electron beam review subsystem configured to review defects detected on the wafer by the optical inspection subsystem; and a computer subsystem configured for: combining, on a defect-by-defect basis, one or more first attributes for the defects determined by the optical inspection subsystem with one or more second attributes for the defects determined by the optical review subsystem thereby generating combined attributes for the defects, wherein the wafer is an unpatterned wafer; separating the defects into bins based on the combined attributes for the defects, wherein the bins correspond to different defect classifications; and sampling one or more of the defects for the review performed by the electron beam review subsystem based on the bins into which the defects have been separated thereby generating a defect sample for the review performed by the electron beam review subsystem.