This summer NWEA will release the 2015 norms. What exactly are norms and why should educators care? Think of social norms. They are the standard or typical behaviors that we expect from all members of our society. Similarly, statistical norms are a way to define typical performance or behavior of various groups usually expressed as percentages or in percentiles. In an educational setting, of course, the groups are students and the performance being captured is often achievement. For NWEA that achievement is both current performance and growth on MAP and MPG.
Educators have always used norms to help parents and students –as well as themselves–understand assessment scores. The norms provide the context that gives a score meaning. Increasingly, in data savvy schools, status norms are used to help make important decisions about student placement in special programs. In addition to using status norms, growth norms are often used by schools for analysis and evaluation of performance and programs. Once schools move beyond simple context to decision making, the quality of the norms becomes even more important. Schools need to have high confidence in the normative data. I will use a summary of how NWEA develops norms and how NWEA suggests norms be used to offer ten key questions that educators should ask before using any normative data.
Norms Development Process
As with any statistical model, norms are most useful when they accurately reflect the population they represent and when they allow for closer analysis of various sub-groups including schools. NWEA is fortunate to have a strong research department that is able to update its norms every three years. In this instance, NWEA waited four years to release new norms to allow the sweeping career and college readiness curricular changes to take hold. Frequently updating norms means the norms reflect the achievement of students in the current instructional environment.
NWEA mines its database of test records given during the last three years to create large nationally representative samples—over 20,000 students per grade–chosen in a way to assure that United States public school demographic groups and geographic regions are appropriately represented in the data set used to compile the norms. Because of the sample sizes and the advanced statistical techniques used to develop NWEA norms, educators can rely on the validity of the data to make important decisions about students, schools and programs. Are the norms current?
- Do the norms represent the right population for our purposes?
- Is the sample population large enough?
- Is there a technical manual that documents procedures?
NWEA provides achievement or status norms for each grade in math, reading, language usage and science. These norms reflect weeks of instruction during the school year rather than simply taking one snapshot. Accounting for weeks of instruction is most easily seen in the 2011 Normative Data with means for fall, winter, and spring for each grade. This feature makes NWEA norms more precise and hence more useful. Teachers can view these norms based on any number of instructional weeks through the year providing a more precise estimate of a student’s current achievement relative to his or her peers. Status norms, presented as a percentile rank, can be useful for placing students into various programs. For example, MAP and MPG scores have met the standards of the National Center for Response to Intervention to be used as a universal screener for placement in RTI. NWEA provides school level norms by subject and grade that parallel the student norms.
- Do status norms account for instructional weeks or only provide one look at grade-level performance?
- What evidence is there that the percentile ranks provided are accurate for screening students for programs?
The real power of MAP and MPG is in measuring growth over time and in being able to compare each student’s measured growth to growth norms. NWEA makes this easy for educators by offering the Conditional Growth Index (CGI) which allows for comparisons based on subject, grade-level, starting RIT and instructional weeks. Using growth norms teachers can understand not only that a student grew but how much that student grew in comparison to other students who had similar starting RIT scores and weeks of instruction. Accounting for instructional progress in growth norms is something only NWEA offers. Growth norms provide teachers the necessary context for setting individual student growth targets, a powerful way to help students take ownership of their own learning. At the school level growth norms express the progress of groups of students and can be useful for making inferences about programs and instructional approaches.
- Are growth norms available and easy to use?
- Are growth norms customizable to reflect individual student starting points as well as grade level?
- Are comparison groups available at the school level reflecting school characteristics?
- Are the growth norms sensitive to weeks of instruction or one size fits all?
Normative data can be a powerful lens for teachers, building administrators and district administrators to view students and programs enabling them to make important decisions and evaluations. However, educators must be sure the lens they use clarifies and does not distort the data.