Interpreting the Percentage of Students Meeting or Exceeding Their Growth Projections

As we come to the conclusion of Spring testing, I find myself answering more and more questions about how to interpret the percentage of students meeting or exceeding their growth projections. I’ve blogged a bit about this topic before, specifically around the use of this statistic for the purposes of teacher evaluation, but I wanted to spend a bit of time talking about the interpretation of this statistic.

First, some background – a student receives a growth projection after his or her first test administration that provides an estimate of what might be considered a reasonable growth expectation for that particularly student. This growth projection is based on three factors:

+ The student’s grade

+ The student’s starting RIT score

+ The subject in which the student was tested

So, a 5th grade student with a Fall RIT score of 200 in mathematics, for example, would have a Fall-to-Spring growth projection of 8 RIT points. Put simply, this growth projection represents our best estimate of the average or typical performance for students in the same grade, in the same subject, and with the same starting RIT score.

Notice that I bolded the words projection and estimate in the previous sentence? I did that to emphasize that these are in fact projections and not definitive benchmarks for where a student should or must be at the end of the year. This is important to keep in mind, as I’m seeing more and more that determinations about the effectiveness of teachers, grades, or schools are being based on the rate at which students are meeting or exceeding these projections. And while the projections do provide extremely useful information to teachers and schools about what constitutes reasonable growth expectations for a student to strive for over the course of the year, they don’t indicate that a student has had a successful school year simply because he or she has met or exceeded that growth projection. Each student brings with him or her a unique set of challenges and strengths, and these should all be considered when interpreting a student’s growth in the context of his or her growth projection (which again, represents average or typical performance).

Further, since these projections provide estimates of average performance, it is important to note that on average, not every student will meet or exceed his or her growth projection – in fact, we generally observe that approximately 50%-60% of students nationwide meet or exceed their growth projections. This is important to note as we have seen districts set learning goals for their teachers or districts that far exceed what we would typically expect to observe. For example, we’ve seen districts where a teacher would be considered ineffective if less than 69% of his or her students met or exceeded their growth projections. While I can appreciate having high expectations for teachers and students, such a system will, on average, result in a high percentage of teachers being rated as ineffective simply because of where the learning bar was set. This also means that if a school or district only has 50% of students meeting or exceeding their growth projections, this shouldn’t be viewed as poor performance – instead, this should be viewed as the students in a school or district showing growth consistent with what we would likely expect to observe. So, as your school year winds down, keep this information in mind as you begin to interpret the percentage of students meeting or exceeding their growth projections, and what that means for your classroom, school, or district.

Still have questions? Leave me a comment below, and I’ll make sure to get it answered. For those of you in the final days or weeks of your school year, good luck, and happy end of the year!