Student Growth Percentiles - Georgia's Student Growth Model

Student Growth Percentiles and TKES

Student Growth Percentiles (SGPs) will be used as the student growth component of the Teacher Effectiveness Measure (TEM) for teachers of tested subjects. SGPs describe a student's growth relative to his/her academic peers - other students with similar prior achievement (i.e., those with a similar history of scores). A growth percentile is generated for each student which describes his or her "rank" on current achievement relative to other students with similar score histories. A growth percentile can range from 1 to 99. Lower percentiles indicate lower academic achievement growth and higher percentiles indicate higher academic growth.

During the full implementation year, SGP performance will be weighted at 50% of the TEM for teachers of test subjects. In addition, a TEM matrix and/or decision tables will be used to determine the impact of the SGP measure on the TEM. The GaDOE will continue to analyze the 2012 pilot data using the draft matrices and make revisions, adjustments, or additions to them as necessary throughout the 2012-2013 implementation year.

The GaDOE will continue to work on matrices and/or decision tables for teachers who have student growth measures from multiple courses with SGP measures, or from both Student Learning Objectives (SLOs) and Student Growth Percentiles (SGPs), so that an appropriate balance is determined between the growth measures, taking into account the number of courses taught with SLOs and the number of courses for which the teacher has SGPs. The GaDOE staff is currently engaged in analyzing possible scenarios and developing detailed processes with technical assistance from external experts.

Student Growth Percentiles and LKES

The SGP summary measure that will be used in calculating the Leader Effectiveness Measure (LEM) is the median growth percentile for all students in the school. The median is obtained by rank ordering the percentiles for all students in the school and selecting the middle percentile (50% of the group would have a higher percentile and 50% a lower percentile). SGPs can be compared across grade levels and across subject areas, meaning summary measures also can be aggregated across grade level and content areas.

During the 2012-2013 pilot/full implementation year, student growth measures from Student Growth Percentiles and Student Learning Objectives will be weighed 50% in calculating the LEM. The GaDOE will continue to work on matrices and/or decision tables for leaders who have school wide student growth measures from multiple courses with Student Growth Percentile measures, or school wide student growth measures from a combination of Student Learning Objectives and Student Growth Percentiles, so that an appropriate balance is determined between the growth measures. The GaDOE will continue to analyze the 2012 pilot data, with technical assistance from external experts, making revisions, adjustments, or additions as necessary, and develop detailed processes throughout the 2012-2013 pilot/full implementation year.

LKES Achievement Gap Reduction

An achievement gap is the difference in student performance between a focal group and a reference group. The focal group is the group of interest while the reference group is the target group. An achievement gap reduction is a decrease in the achievement gap from one school year to the next. The goal of measuring achievement gap reduction is to focus on increasing the achievement of schools' focal groups, which are schools' lowest achieving students.

In this calculation, a focal group will be compared to a reference group. The focal group is schools' high-need students, which is defined as the lowest 25% of students in the score distribution. The reference group is a statewide benchmark, defined as the state's mean performance. This represents an ambitious, yet attainable goal. Using a statewide benchmark as the reference group increases the stability of the measure as well as eliminates the ability to improve on the measure by decreasing the achievement of higher achieving students. A reference year for the benchmark will be used in calculations, ensuring schools are not being measured against a moving target.

The gap measure includes two components - a gap size and gap change. Gap size is defined as the difference in achievement between the state benchmark and the school's high-need students. Gap change is defined as the gap size for the current year minus the gap size for last year. For each subject area, a school's final score will be the higher of the gap size and gap change score. The overall final score will be the average of the final subject area scores.