Measuring Teacher Effectiveness FAQ

Measuring teacher effectiveness is an extremely complex and important topic. RAND Education and Labor's experts have answered some of the most frequently asked questions about this policy issue, providing clear, concise, but rigorous answers.

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I know that teachers are important, but exactly what kind of impact do they have on student achievement?

Research suggests that, among school-related factors, teachers matter most when it comes to a student's academic performance. Nonschool factors do influence student achievement, but effective teaching has the potential to help level the playing field.

Teachers Matter: Understanding Teachers' Impact on Student Achievement

How can we measure teaching effectiveness?

Teaching is a complex activity that should be measured with multiple methods. These include:

Student test scores
Standardized tests provide an efficient way to measure how well students have learned basic content.
Classroom observation
Observation measures teaching practices directly. However, this usually requires more time and money than test-based estimates of teaching effectiveness.
Surveys and other methods

Many school districts and states use student and parent surveys to measure teaching effectiveness. Other options include tests of teachers' knowledge and skills; participation in professional development, committees, or mentoring; and input from peers or administrators.

However, these measures have not been as thoroughly examined by researchers as test-based or observation methods.

Multiple Choices: Options for Measuring Teaching Effectiveness

What do student achievement tests tell us about teacher effectiveness?

Test scores tell us a lot about achievement in reading and math but less about achievement in other subjects. Moreover, tests don't often fully assess important skills, such as problem solving and teamwork. Information from test scores should be combined with other measures—such as classroom observations and input from supervisors and peers—to evaluate a teacher's full contribution.

Tests and the Teacher: What Student Achievement Tests Do—and Don't—Tell Us About Teacher Effectiveness

What is value-added modeling, and how can it measure a teacher's impact on student achievement?

Value-added models, or VAMs, attempt to measure a teacher's impact on student achievement apart from other factors, such as individual ability, family environment, past schooling, and the influence of peers. Rather than focusing on how students test at a single point in time, VAMs estimate how much improvement they make from one testing period to the next.

Value-added estimates enable relative judgments but are not absolute indicators of effectiveness.

Value-Added Modeling 101: Using Student Test Scores to Help Measure Teaching Effectiveness

What are student growth percentiles? How can they measure teaching effectiveness?

Student growth percentiles, or SGPs, provide a simple way of comparing the improvement of one teacher's students with the improvement of other students. SGPs show how a students' achievement at the end of the year compares with that of other students who started the year at the same level.

Unlike value-added modeling, using SGPs to measure a teacher's effectiveness does not account for variations among students or classes, nor does it indicate what caused the improvement. However, SGPs are easier to understand than many other complex statistical models and can provide most teachers and parents with a clear indicator of progress for each student.

Student Growth Percentiles 101: Using Relative Ranks in Student Test Scores to Help Measure Teaching Effectiveness

The Measuring Teacher Effectiveness Fact Sheet Series