Another potential refinement of the scale, which raises both theoretical and empirical issues, involves its dimensionalities. As exhibit 5 indicates, there is relatively little difference between the three- and four-dimension models. I have chosen to retain selfsacrifice as an independent dimension on substantive grounds because it has had a historical connection to how we think about public service that is explicitly preserved by retaining the dimension. Although I have retained the self-sacrifice dimension in the final model, a three-factor solution coincides with Knoke and Wright-Isak's (1982) rational, norm-based, and affective dimensions of motivation. Because these dimensions are part of the theoretical underpinnings of the scale (Perry and Wise 1990), they are also plausible as an empirical result. The resolution of the precise dimensionalities of the scale must await results from future administration of the scale