I noticed the Math percentiles changed in the summer of 2020. How are the percentiles chosen for the easyCBM progress monitor tests?
The raw score-percentile associations changed around the summer of 2020 because we recalculated the norms for all easyCBM measures using a more current draw of thousands of students from our database ––stratified by region and demographic groups where we had enough students. While norms by and large remain relatively stable over time, they can change. So, we periodically recalculate the norms, typically every 5 years, so that teachers/schools/districts have an accurate picture of what student performance looks like from the lower to the higher end of the performance continuum because demographics and teaching practices shift over time. In other words, norms are updated so that we provide an up-to-date indication of how students are performing relative to teach other at a given point in time (e.g., fall, winter, and spring benchmark assessments and the progress-monitoring that takes places for some students in between those seasonal benchmark administrations).
The percentiles and scores in Progress Monitoring (https://app.easycbm.com/static/files/pdfs/info/ProgMonScoreInterpretation.pdf) and Detailed Percentiles Table (https://app.easycbm.com/static/files/pdfs/info/easycbm_percentile_lookup_table.pdf) documents were calculated using a nationally representative stratified norm sample, with approximately 500 students drawn from each of four regions (West, Midwest, Northeast, Southeast), for a total sample of 2,000 students per measure per grade. These norms were developed in 2020 and will be updated in 2025 (and on a five-year rotation thereafter).
A technical report is available that goes into more detail on how we calculate norms –– it can be found here: https://www.brtprojects.org/wp-content/uploads/2016/05/TechRpt1409_easyCBM_Norms.pdf