Many legislative recruitment scholars seek to explain why women, visible minorities and other social groups are underrepresented in the world’s legislatures. Researchers in this area often use a supply and demand metaphor to frame their work, but cannot agree whether under-representation is mainly a supply- or demand-side problem. With an eye to moving this debate forward, this article offers a new approach to operationalizing supply and demand and shows how reverse-flow diagnostic testing, supply-first analysis and an improved testing regime can pinpoint when and why under-representation begins to occur in any political system. The new diagnostic approach is applied to data from a provincial election in British Columbia, Canada. The article uses the new diagnostic and BC case to demonstrate how under-representation in any political system is attributable to demand-side discrimination by gatekeepers and not an under-supply of political aspirants from any particular social group.
