Student Growth Percentile

Student Growth Percentile (SGP), developed by Dr. Damian Betebenner, provides the latest in growth projections, including Betebenner's well-known catch-up, keep-up growth projections to provide longitudinal SGP data.

Student Growth Percentile is calculated for students who have taken at least two tests (a current test and a prior test) within at least two different testing windows (Autumn, Winter or Spring). The current test is the most recent test the student has taken in the most recent window that the student has tested in within the last 18 months. The prior test(s) are from the most recent SGP test window before the one that the current test falls in.

If a student has taken more than one test in a single test window, the SGP calculation is based off the following tests:

  • The current test is always the last test taken in a testing window.
  • The test used as the prior test depends on what testing window it falls in:
    • Autumn window: The first test taken in the Autumn window is used.
    • Winter window: The test taken closest to January 15 in the Winter window is used.
    • Spring window: The last test taken in the Spring window is used.
Type of SGP Score Test Scores Used
Autumn to Spring Current Spring, Current Autumn and Previous Spring
Autumn to Winter Current Winter, Current Autumn and Previous Spring
Winter to Spring Current Spring, Current Winter and Current Autumn
Spring to Autumn Current Autumn, Previous Spring and Previous Winter
Spring to Spring Current Spring, Previous Spring and the Spring before the Previous Spring
Autumn to Autumn Current Autumn, Previous Autumn and the Autumn before the Previous Autumn

Note: If a student is held back a year, SGPs will be calculated for that student using the previous school year's testing data. A held-back student needs to take two tests in two separate testing windows in the current school year before having an SGP calculated using the current school year's testing data.

Conditions in which an SGP cannot be calculated:

  • When no tests were taken in the past 18 months
  • When the only tests taken in the past 18 months are in the same window
  • When some of the Star Maths assessments that would be used were taken before Year 2
  • Spring to Winter
  • When a student's assigned year is different during a school year for two different testing windows
  • When the data available was imported after the end of an SGP window (so no SGP is calculated for the next window)
  • When the year associated with the Star Maths test is greater than year 13

Student Growth Percentile utilises the historical growth trajectories of Star examinees to map out what the range of potential growth trajectories for each student will lead to, including what growth is necessary for each student to reach/maintain proficiency. The SGP is updated regularly so that students' projections are based upon the most recent data available. SGP is calculated using data from both US and UK students.

You will see the SGP on the fan graph for the student.