School size, student achievement, and the "power rating" of poverty: Substantive finding or statistical artifact?


  • Theodore Coladarci University of Maine



small schools, student achievement, socioeconomic status, , rural education.


The proportion of variance in student achievement that is explained by student SES-"poverty's power rating," as some call it-tends to be lower among smaller schools than among larger schools. Smaller schools, many claim, are able to somehow disrupt the seemingly axiomatic association between SES and student achievement. Using eighth-grade data for 216 public schools in Maine, I explored the hypothesis that this in part is a statistical artifact of the greater volatility (lower reliability) of school-aggregated student achievement in smaller schools. This hypothesis received no support when reading achievement served as the dependent variable. In contrast, the hypothesis was supported when the dependent variable was mathematics achievement. For reasons considered in the discussion, however, I ultimately concluded that the latter results are insufficient to affirm the statistical-artifact hypothesis here as well. Implications for subsequent research are discussed.


Download data is not yet available.

Author Biography

Theodore Coladarci, University of Maine

Theodore Coladarci is Professor of Educational Psychology at the University of Maine. Since 1992, he has served as editor of Journal of Research in Rural Education ( An earlier version of this work was presented at the 2006 meeting of the American Educational Research Association, and the author wishes to thank the discussant, Aimee Howley, for her thoughtful comments and suggestions. The author also is grateful for the feedback provided by Deb Allen, Sandy Ervin, Ed Kame’enui and the four anonymous reviewers.




How to Cite

Coladarci, T. (2006). School size, student achievement, and the "power rating" of poverty: Substantive finding or statistical artifact?. Education Policy Analysis Archives, 14, 28.