“…Because many of the 44 DOT variables overlap, previous researchers attempted to derive meaningful job characteristic dimensions by subjecting the variables to factor analysis. Although there is some variability in results, these analyses frequently yield four distinguishable factors (Hayward, Friedman, & Chen, 1998;Miller et al, 1980;Parcel, 1989). These factors have been labeled (a) substantive complexity, representing the degree to which a job requires handling data and requires high levels of training or preparation; (b) manipulative skills, or the extent to which jobs require working with "things" and require motor coordination, finger dexterity, and eye-hand coordination; (c) physical and environmental demands, or the extent to which a job involves strength and exposure to extreme temperatures or environmental hazards; and (d) social skills, or the extent to which a job requires dealing with people and requires the physical capabilities of talking, hearing, and seeing.…”