What Percentage of Students Meet their Growth Targets?

In NWEA’s norms, about what percentage of students who take MAP assessments typically meet their school year growth goals?

This is a tough question to answer, since it’s not something that we specifically report or rank within our current school norms.  Each student’s growth goal is simply the mean (or average) normative growth, which considers a student’s enrolled grade, initial achievement level, and the number of weeks of instruction received.  Even within the same grade within a single school, one student’s growth goal may be larger than another’s, depending on their initial achievement levels.  Consequently, it can be misleading to simply report and aggregate the percentages of students meeting growth targets without considering all the variables that give rise to different growth goals.

growth goals

Each student’s growth goal (i.e., average normative growth) is described by a bell curve with a specific mean and standard deviation.  For example, Student X may have a normative growth distribution with a mean of 8 and a standard deviation of 4. If that student made 8 points of growth, he/she would be right at the center of the distribution.  In the most general sense, about 50% of students show growth that is greater than mean normative growth, and about 50% show less than mean normative growth, as implied in the bell curve figure above. So in a general sense, one could reasonably expect that about 50% of students should meet their growth goals.

Similar bell curve distributions describe school (or, more accurately, grade level) normative growth on MAP assessments. Such growth distributions depend on the grade, subject, average starting achievement (i.e., average starting RIT score for the group), and number of weeks of instruction received.  When school (grade level) growth is described by a normal distribution, generally about 50% of the group will exceed mean growth and about 50% will fall below that goal.

What our school growth norms do not do is to account for specific demographic compositions within a school.  NWEA school norms are based on a representative sampling of schools from across the country, and so our school norms will be appropriate for schools whose racial demographics parallel the racial distributions of the U.S. student population.  For school settings that vary greatly from national U.S. distributions, we may also be able to create custom tailored sets of growth norms for specific school settings by creating Virtual Comparison Groups (or VCGs) that match students to other similar students across the country in comparable school settings.   The observed growth of the virtual comparison group is then used to estimate a normative growth distribution for that student.  Using this approach, the percentages of students whose growth meet/exceed their growth goals still hover around 50%, but these growth goals are tailored to more precisely resemble the specific school setting attended by the students.

NWEA is happy to offer technical resources and guidelines and to work with our partner school districts to establish reasonable student and school level growth goals based on NWEA student and school norms.