The Relative Influence of Research on Class Size Policy

Social science research suggests that reducing class size has its largest effects on the achievement of minority and inner-city children during the first year of formal schooling.¹ Despite scholarly disagreements about the implications of specific studies on class size, economists generally agree that targeted class-size policies rest on stronger evidence than untargeted policies. For example, economist Eric Hanushek contends that "surely class-size reductions are beneficial in specific circumstances—for specific groups of students, subject matters, and teachers."² Similarly, economist Alan Krueger notes that the "effect sizes found in the STAR experiment and much of the literature are greater for minority and disadvantaged students than for other students [and] economic considerations suggest that resources would be optimally allocated if they were targeted toward those who benefit the most from smaller classes."³ However, a number of state legislatures have enacted untargeted and expensive policies to reduce class sizes in all schools, among all subgroups of students, and beyond the early elementary grades. Therefore, the central tension between research and policy in the class-size debate is this: research seems to support targeted class-size policies most strongly, but targeted policies are the exception rather than the norm in the policy arena. As a result, some social scientists have criticized across-the-board class-size reductions as prohibitively expensive and scientifically indefensible.⁴

The Politics of Class Size

In this paper, I argue that the influence of social science research on class-size policy depends partly on political context. Instead of simply asking whether research affects policy, it is equally important to examine how the politics of the class-size debate shape the many uses of research in the policy arena. Social scientists cannot control the uses of research, but they can encourage evaluation of policies in terms of their effects on educational outcomes. Social scientists possess methodological tools rather than policy prescriptions, and research is a valuable resource because it helps clarify the goals of public policies without dictating the outcome of democratic debate.

Table 1.

Classifying and Explaining the Politics of Class-Size Reduction Policies

Political scientist James Q. Wilson provides a way of classifying the politics surrounding policy issues such as class-size reduction. Wilson's framework can help identify some conditions under which research may influence public policy. As shown in table 1, untargeted class-size reduction represents a popular education policy that distributes benefits and costs among a large number of people. Public opinion polls suggest that a majority of voters—including teachers, superintendents, parents, and taxpayers—support reducing class sizes in order to improve their local schools.⁵ When legislators cast class-size reduction as "majoritarian issue," the proposal appeals to large blocs of voters and it is generally easy to form a majority coalition supporting it. A recent example of an untargeted class-size policy is the 2002 Florida class-size amendment, which was supported by a motley collection of voters—senior citizens, union leaders, parents, and educators—who approved a multibillion-dollar policy that mandates a cap on class size in elementary, middle, and secondary schools by 2010. The Florida policy, as well as similar untargeted class-size policies in California and Nevada, follows the prediction advanced by Wilson's framework: "If a new policy is adopted and people become convinced that the promised benefits are real and worth the cost, debate ends and the program will not only continue but will also grow rapidly in size."⁶ Widespread political support is sufficient to legitimize an untargeted class-size reduction policy. Therefore there is little incentive for legislators to plan for evaluation of a popular policy whose central goal is to advance political interests rather than to achieve preset educational goals.

Table 1 also shows that targeted class-size reduction policies distribute costs and concentrate benefits among "clients" of government. According to Wilson, when "benefits are concentrated, the group that is to receive those benefits has an incentive to organize and work to get them."⁷ Evidence plays a more vital role in helping...