The Logic of Congressional Elections

Richard Keiser, Carleton College
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This material was developed as part of the Carleton Teaching Activity Collection and is replicated on a number of sites as part of the SERC Pedagogic Service Project


Is America really divided between Red and Blue states, or are most states more heterogeneous than this popular dichotomy suggests? Does one or the other political party demonstrate an edge in open seat elections where no candidate enjoys the advantages of incumbency and the parties compete on a level field? How significant is electoral competitiveness (i.e., where only a small share of the vote separates winner from loser) as an explanation of voter turnout in congressional elections? Students will analyze data to answer these questions and also discover the significance of intervening variables such as incumbency, region, and presidential coattails in quantitative and qualitative analyses.

Learning Goals

  1. Distinguish between antecedent, independent, intervening and dependent variables.
  2. Anticipate biases in data selection that might skew hypothesis testing.
  3. Practice techniques of the visual presentation of data.

Context for Use

Appropriate for undergraduates in introductory courses or courses on Congress. With large classes, students may be able to work in teams and tackle more data. Ideally, exercise can be structured with an opportunity for revision. Students without statistical skills can do these assignments using simple percentages.

Description and Teaching Materials

Standard reference books of national electoral statistics such as CQ's Politics in America or National Journal's Almanac of American Politics provide most of the necessary data. Both of these are available online, in easily searchable formats. Voter registration data are available from state offices of the Secretary of State. Electoral Competitiveness and Turnout in Senatorial Elections (Microsoft Word 57kB Sep19 08) Red, Blue or Purple States: Measuring State Electoral Homogeneity (Microsoft Word 82kB Sep19 08) Open Seat Elections and Partisan Strength in House of Representatives Elections (Microsoft Word 61kB Sep19 08)

Teaching Notes and Tips

Assignment can be made more/less challenging by removing/adding hints about potential intervening variables (e.g., presidential election years, voter registration rules) from instructions.


Grading each paper; student self-assessment after assignment; post-assignment discussions among students who chose the same assignment; growth from first draft to revision; improvement from first assignment to a second topic.

References and Resources