NCPA - National Center for Policy Analysis

Buckeye Institute: There is Little Evidence Class Size Matters

May 14, 1999

Reducing class size may not improve student achievement, two new studies conclude. The studies are especially important in light of Tennessee's Project STAR, which claimed to show improvement in student achievement following class-size reduction. From 1985 to 1989, Project STAR attempted to track student achievement in both big and small classes from kindergarten through third grade.

Conducted separately by economists Eric A. Hanushek of the University of Rochester and Caroline M. Hoxby of Harvard University, the studies question the wisdom of proposals for reducing class size.

Hanushek's study -- "Some Findings from an Independent Investigation of the Tennessee STAR Experiment and from Other Experiments of Class Size Effects," to be published in Educational Evaluation and Policy Analysis -- found that STAR's poor methodology exaggerated benefits from class-size reduction. For instance:

  • Between 20 and 30 percent of the students quit the project each year, with less than half the original number remaining at the end.
  • The students who quit tended to be below-average achievers, giving the smaller classes a perceived boost in achievement.
  • No pretests were conducted on any students upon enrollment, which provided no benchmark to assess their level of achievement.
  • Neither the teachers nor the schools chosen for the project were selected randomly.

Hoxby's study -- "The Effects of Class Size and Composition on Student Achievement: New Evidence from Natural Population Variation," published by the National Bureau of Economic Research -- found that reductions in class size within the range of 15 to 30 students had no effect on achievement. Hoxby criticized Project STAR, stating that its participants were "aware of being evaluated" and "mindful of the rewards being contingent upon the outcome."

Source: "Two New Studies Cast Doubt on Benefits of Class-Size Reduction," Policy Note, May 1999, Buckeye Institute for Public Policy Solutions, 131 N. Ludlow Street, Suite 317, Dayton, Ohio 45402, (937) 224-8352.


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