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Misconception: TVAAS reporting is not reliable or valid since it is based only on standardized assessments.

Educators might be concerned that value-added reporting relies on the use of standardized tests, which have limitations themselves. Perhaps they feel that the test does not correlate well with the curriculum or that there isn't sufficient stretch to measure progress of very low- or high-achieving students. However, TVAAS estimates use a sophisticated modeling approach to address many of the concerns of using standardized tests, and SAS reviews the test scores annually to ensure that they are an appropriate use for TVAAS value-added reporting.

TVAAS in Theory

Student test scores are the basic ingredient of all TVAAS analyses. TVAAS is not involved in and has no control over test construction. TCAP, EOC, and Grade 2 assessments are aligned to the appropriate grade- and subject-level state standards that are sufficient for longitudinal modeling and prediction. Regardless, before using any tests in TVAAS modeling, rigorous data processing and analyses verify that the tests meet the following three criteria:

  • Must be designed to assess the academic standards.
  • Must be reliable and valid (usually related to the number of test questions).
  • Must demonstrate sufficient stretch at the extremes.

To date, TCAP, EOC, and Grade 2 assessments have met these criteria. More specifically, TVAAS analyses verify that there are enough different scaled scores at the top and bottom of the scales to differentiate student achievement. This processing also analyzes the percentage of students scoring at the top and bottom scores to ensure there are no ceilings or floors. After all analyses are completed and TVAAS estimates are available, SAS verifies that systems, schools, and teachers serving both high- and low-achieving students can show both high and low growth. This process is repeated every year.

TVAAS in Practice

Actual data may be the most readily apparent way to show that there is sufficient stretch in Tennessee's state assessments to measure the growth of low-, middle-, and high-achieving students. The figure below plots the average achievement for each school in Tennessee against the growth index (the value-added growth measure divided by its standard error) for TCAP Mathematics in grades 4–8 in 2019. The figure demonstrates that schools serving both high- and low-achieving students can show both high and low growth, as measured by TVAAS.

TENNESSEE GROWTH INDEX VERSUS AVERAGE ACHIEVEMENT BY SCHOOL