NCPA - National Center for Policy Analysis


September 19, 2005

State education plans that measure aggregate student scores by school may overlook an important component of overall education quality: teacher quality variation within a school, according to the National Bureau of Economic Research.

The authors used data from the Texas School Microdata Panel to measure teacher quality by thee annual growth in each student's scores on the mathematics section on the Texas Assessment of Academic Skills (TAAS). They find that:

  • First-year teachers have much lower performance on average than other teachers.
  • Teacher performance improves markedly, peaking in a teacher's fourth year.
  • This could partially explain the poor performance of urban schools, because urban schools suffer higher teacher turn over and thus have a greater proportion of first-year teachers than other schools.

The authors also report that there is substantial variation in teacher quality within schools. This has major implications for state accountability programs:

  • Many states measure quality by aggregate student scores for an entire school, not by classroom or teacher.
  • Consequently, state programs miss vital differences between teachers inside the same school.
  • This weakens the incentives for good teachers to enter and remain in teaching, for ineffective teachers to leave, and for all teachers to put forth greater effort.

Source: Linda Gorman, "Good Teachers Raise Student Achievement," NBER Digest, August 2005: based upon: Eric Hanushek, John Kain, Daniel O'Brien and Steven Rivkin, "The Market for Teacher Quality," National Bureau of Economic Research, Working Paper No. 11154, February 2005.

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