How does Categorical Growth Analysis work?
The Categorical Growth Analysis (CGA) model provides an objective evaluation of the magnitude of student growth. ATI uses the CGA approach to evaluate student growth from the pretest to the posttest that can be applied even to individual classrooms, regardless of district/charter school size. This is how the approach works:
- Cut scores for the pretest and posttest are established. The cut scores on the posttest are raised relative to those on the pretest by the amount of progress that is expected over the course of the year. The posttest cut score is based on the average expected growth across a large number of districts.
- Classify students at Time 1 (the first test/pretest) with regard to whether they demonstrated mastery of the state standards.
- At Time 2 (the second test/posttest), track whether each student's mastery classification stays the same as it was at Time 1, or changes.
- Focus on the students who changed mastery status from Time 1 to Time 2.
- The hope is that more students will have moved from non-mastery to mastery than from mastery to non-mastery.
- Conduct a chi-square analysis to determine if the number of students moving in one direction is significantly greater than the number of students moving in the other direction.
- Expected growth is not maintained. This outcome is supported in those instances in which there is a significant decrease in the relative proportion of students achieving standards mastery.
- Expected growth is maintained. This outcome is supported in those instances in which there is no significant change.
- Expected growth is exceeded. This outcome is supported in those instances in which there is a significant increase in the relative proportion of students achieving standards mastery.