VAM Requirements and Covariates

The following list of VAM requirements and covariates help ensure the best possible estimates of teacher and school performance based on student growth.

VAM Requirements and Covariates
Student-level Variables
  • Full academic year (FAY = 1)
  • Pre-test/post-test scoring in the primary subject (i.e., “on-subject” test performance”)
  • Pre-test scoring in related subject (i.e., “off-subject” test performance)
  • Student-level demographic variables:
  • Eligible for free-and-reduced priced lunch
  • Eligible for English language learner services
  • Eligible for special education services
/ School-level Variables
Note: The following are generated from using the student-level variables
  • Average “on-subject” pre-test generated at the grade-level for each school
  • Average “off-subject” pre-test scoring generated at the grade-level for each school
  • Grade-level demographic variables by school:
  • Percent of students eligible for free-and-reduced priced lunch
  • Percent of students eligible for English language learner services
  • Percent of students eligible for special education services

Specifically, use of the pre-test enables the model to assess the change in student academic performance over the school year. Off-subject pre-test scores and the grade-level pretest averages are included because they have been shown in prior studies to significantly reduce the bias of VAM estimates. The student- and grade-level demographic variables in the model help control for factors beyond the control of the teacher or school, thereby ensuring that personnel decision-making based on the evaluation model does not disadvantage educators in unique situations, such as special educators whose students’ year-to-year academic growth may systematically differ from that of general education students.

In addition, the following assessment and model estimate considerations were required:

Assessment Requirements: / Model Estimation Requirements:
  • Scale scores
  • Assessment standard error of measurement (SEM), by scale score
  • Documentation of equivalency across test forms
  • Comprehensive assessment manual outlining the psychometric studies carried out in the development of the assessment, how scales are produced, horizontal (across form) and vertical (across time) equating, etc.
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  • For individual level models:
  • Educator eligibility status (EPP = 1)
  • A minimum of 10 students per educator
  • A minimum of 10 educators with 10 students each
  • For school level models:
  • A minimum of 10 students per school
  • A minimum of 10 schools with 10 students each
  • Assessment scale score reliability must be relatively high to facilitate model estimation (ideally above .80, noting that above 0.90 is generally recommended for decision making purposes)