Value-Added Assessment
Helen Raham, Fall 2000
Some are calling it the accountability revolution. A dozen states
and many school districts across the USA have begun to use value-added measures to assess
system, school and even teacher performance. In Colorado alone, some 65 districts have
signed up to try the new assessment methods.
Dr. William Sanders, the researcher who pioneered the sophisticated statistical
techniques, is the hottest speaker on today’s education circuit. He recently left the
University of Tennessee’s Value-Added Research and Assessment Centre to join a
software company where he will assist other states and school districts develop
value-added measurement systems.
Value-added assessment is a statistical tool for gauging academic gains attributable to
the school in a given year. A longitudinal profile is created for each student by
collecting achievement scores over a period of time. New techniques allow researchers to
use these data to estimate with considerable sensitivity the relative effectiveness of
school districts, schools and teachers in creating academic progress.
Measuring Schools
Current achievement is compared to past performance to assess the school’s annual
contribution to student progress. A complex mathematical formula factors out many of the
variables such as student socioeconomic levels that make conventional comparisons of
schools problematic. Policymakers find the technique attractive because it can be used to
evaluate schools without penalizing those with many disadvantaged pupils.
The Tennessee system works like this:
In April each year, students in Grades 3-8 take the state
tests in 5 core subjects. The new test scores are merged with results from previous years
and examined by classroom, school and district to find the patterns.
In the fall, schools receive a report card summarizing how
each grade progressed in every subject over the previous year, based on national norms.
These results when combined with other indicators are used to determine state rewards for
schools and sanctions for districts.
Each teacher receives a report card (not made public)
revealing the progress of his or her students.
Evaluating Teachers
A second generation of value-added assessment is being used to produce an indicator of
teacher effectiveness. Applied to the aggregate scores of students taught by an individual
teacher, it can help identify over time which teacher’s students are learning the
most and which are learning the least. This application has been studied for a number of
years by other researchers in Dallas, Boston, Chicago, Minneapolis, California and
Alabama.
Findings
Robert Mendro has tracked student performance in Dallas since 1993. By using 16 factors to
group students by gender, race and socioeconomics, he was able to compare like students
with like. From these data, Mendro created a five-tier rating system (from most to least
effective) for 4,500 district teachers. He then studied the cumulative effects of teacher
proficiency on students by comparing two groups of primary students with above average
Grade 1 reading scores. The children assigned to weaker teachers for three years running
had dropped from the 63rd to 22nd percentile by Grade 4. The group
assigned to average or stronger teachers was performing at the 67th percentile
in Grade 4.
The Tennessee system also provides evidence to suggest that the single largest factor
affecting the academic growth of students is the difference in teacher effectiveness.
Finding stark cumulative effects that cannot be made up, Sanders says it is critical that
ineffective teachers be identified. "The evidence is overwhelming that with two very
weak teachers in a row, unless there is a major intervention, that kid never recovers. And
that is something as a society we cannot ignore"
Policy Implications
Many are skeptical that v-a assessment can account for the wide range of variables that
influence student achievement. Nevertheless, many believe it is a useful thermometer whose
benefits include helping identify teachers most in need of assistance.
The policy implications are far-reaching. It may enable educational decision-makers and
the public to see more clearly which schools are working. It promises a more objective
standard for evaluating both school and teacher effectiveness. It suggests a means of
targeting scarce professional development funds and a basis for pay-for-performance plans.
Factored into teacher assignments, it could ensure equal opportunity to learn for all
groups of students.
Applications in Canada
Several provinces are now exploring value-added assessment. In most provincial systems the
information management technology is in place, but additional data collection will be
required, including annual achievement scores by grade in core subjects and student SES
data by school.
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