A power measure analysis of Amendment 36 in Colorado

Colorado’s Amendment 36 proposed to switch Colorado’s representation in the Electoral College from winner-takes-all to proportionality. We evaluate unilateral and uniform switches to proportionality both from Colorado’s perspective and from an impartial perspective on the basis of a priori and a posteriori voting power measures. The present system is to be preferred to a unilateral switch from any perspective on any measure. A uniform switch is to be preferred to the present system from Colorado’s perspective on an a priori measure, and from an impartial perspective on an a posteriori measure. The present system is to be preferred to a uniform switch from Colorado’s perspective on an a posteriori measure (with some qualifications), and from an impartial perspective on an a priori measure. We conclude with a discussion of the appropriateness of these measures.