NCPA - National Center for Policy Analysis


September 28, 2005

Good teachers increase student achievement, according to a recent paper from the National Bureau of Economic Research.

Coauthors Eric Hanushek, John Kain, Daniel O'Brien and Steven Rivkin used a unique dataset from the Texas School Microdata Panel to measure teacher quality by the annual growth in each student's scores on the mathematics section of the Texas Assessment of Academic Skills. The dataset links detailed student, teacher and school characteristics in grades 4 through 8 for the 1995-96 and 2000-01 school years in a major Texas urban district.

The authors found:

  • The average student who has a teacher at the 85th quality percentile can expect annual achievement gains greater than the average student with a median teacher.
  • Good teachers do well with students at all levels of achievement, and there is no evidence that teacher education or performance on a certification examination contributes to quality teaching.

The authors believe that the latter findings raise "serious questions both about the desirability of requiring or rewarding with higher pay those with a post-graduate degree and about the efficacy of the existing certification procedures in Texas and similar systems in other states." Moreover:

  • First-year teachers have much lower performance on average than other teachers.
  • After that, teacher performance improves markedly, peaking in a teacher's fourth year.
  • In Texas, 10 percent of teachers with less than 3 years' experience, and 7 percent of all teachers, leave each year.

Because first-year teachers are at a disadvantage, to the extent that higher turnover in urban school districts increases the proportion of first-year teachers, high turnover may be part of the explanation for their poorer performance, say the authors.

Source: Hal R. Varian, "Tenure, Turnover and the Quality of Teaching," New York Times, September 22, 2005; and Linda Gorman, "Good Teachers Raise Student Achievement," NBER Digest, August 2005; based upon: Eric A. Hanushek et al., "The Market for Teacher Quality," National Bureau of Economic Research, Working Paper, No. 11154, February 2005.

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