The percentile ranking on your child’s score report compares their score to the scores of children in the sample group that is the same grade and season. Currently we are using 2015 norms. Here is some information about the sample groups:
Each sample is comprised of 72,000 to 153,000 student test records from approximately 1000 schools. These
numbers vary by subject. These samples were drawn randomly from test record pools of up to 10.2 million students attending more than 23,500 public schools spread across 6,000 districts in 49 states. Rigorous procedures were used to ensure that the norms were representative of the U.S. school-age population.
A child who scores in the 55th percentile has a score that is higher than 55% of the sample group. A child who scores in the 90th percentile has a score that is higher than 90% of the sample group. The highest possible percentile ranking on our score reports is 99.