In practice, votes cast in parliamentary and related elections receive more weight as they are more representative. That practice is difficult to rationalize either from a juridical constitutional-democratic, or an economist preferential-choice point of view. On an applied-psychometric basis, the author presents a rationale by which voters are conceived as evaluators of political parties' programs, candidates, and past performance. That conception leads to a general weighting model, of which both strict proportionality (unit weighting) and strict plurality (dichotomous weighting) appear to be special cases. The model appears to develop its full potential in a combination with an otherwise impractical dual ballot structure, by which voters can indicate a desired coalition partner, as illustrated by a fictive example. Reservations with respect to the model and its rationale are discussed.