Immediately after her swearing-in ceremony in January 2007, Minnesota's new senator, Amy Klobuchar, began representing her constituents in the Senate. Within the first few days, Klobuchar cast roll-call votes to support ethics reform and to raise the minimum wage, fulfilling campaign promises. Klobuchar also sought out desirable committee assignments. She lobbied hard for, and obtained, a seat on the Senate Agriculture committee – a useful assignment for a senator from farm-rich Minnesota (Staff 2007). Klobuchar also organized her Senate office, hiring a staff that included a former farm bureau president as “a key adviser on farm policy” (Averill 2007). And Klobuchar decided how to invest her time and efforts in the Senate (Hall 1996). Early on, she actively participated in committee hearings on the Agriculture Committee (Klobuchar 2007g) and drafted a letter to protect the market for Minnesota beef in South Korea (Klobuchar 2007h).

Klobuchar's work after arriving in Washington – the roll-call votes cast, the hiring of staffers, and the advocacy for Minnesota farmers – comprises components of the representation she provided constituents. Five decades of scholarship on representation has analyzed these sorts of decisions (e.g., Eulau et al. 1959; Miller and Stokes 1963; Achen 1978; Griffin and Newman 2005). The goal of this work is to measure fit: the correspondence between what legislators do in Washington and what constituents want them to do. The best-studied facet of fit is legislators' roll-call voting behavior.