Colorado Growth Model as a teacher-effectiveness measure based on student growth percentiles¶

Theory · All theories
Evidence · 6 claims (4 for, 1 mixed, 1 against) · 4 studies (4 associational), q2 · 0 of 4 report an effect size · 6 claims rest on one study

Description¶

The Colorado Growth Model (CGM) assigns each student a growth percentile by comparing the student's achievement to that of other students with similar past test scores; the median or average growth percentile of a teacher's students serves as the teacher-effectiveness measure. The article notes the "CGM does not account for other student background characteristics and excludes other features included in many value-added models." Sixteen states currently use or plan to use it as a component of teacher performance evaluations.

Design Implications¶

Context¶

Requirements¶

• Student test-score data allowing comparison of each student's achievement to students with similar past test scores

Constraints¶

• Does not account for other student background characteristics
• Excludes other features included in many value-added models used by states and school districts

Target Learners¶

• K-12 students in states using the CGM for teacher evaluation

Target Learning Objectives¶

• Measuring teacher effectiveness in raising student achievement

Claims¶

• Cgm Versus Value Added Changed Evaluation 14 Percent Dcps [+M]
• Most differences in evaluation scores between the Colorado Growth Model and value added are not related to the characteristics of students' teachers [~W]
• Using the Colorado Growth Model in place of a value-added model increases evaluation scores for teachers of low-achieving students [+W]
• Using the Colorado Growth Model in place of a value-added model depresses evaluation scores for teachers with more English language learner students [-W]
• School median student growth percentiles were stable year to year even when the school changed principals [+W]
• Principal practice instrument ratings and school median student growth percentiles showed moderate to high year-to-year stability, but growth percentiles changed more across years in smaller schools [+W]

Related Theories¶

Examples¶

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Key Sources¶

• Elias Walsh, Eric Isenberg. (2015). How Does Value Added Compare to Student Growth Percentiles? Statistics and Public Policy, vol. 2, issue 1. https://www.mathematica.org/publications/how-does-value-added-compare-to-student-growth-percentiles