How we estimate percentiles: Minnesota high school

A clear explanation of the data and the method, so you can judge how much weight to give the numbers.

What the data is

Every number here comes from the Minnesota Department of Education’s public assessment files for the Minnesota Comprehensive Assessments (MCA): grade 10 Reading, grade 11 Math and the high school Science test, for 2018, 2019 and 2021 to 2026. These files report, for each school, district, county and the state:

the real number of students in each achievement level and the number tested, each published by the Minnesota Department of Education, and
Minnesota’s own published average scale score and standard deviation (how spread out the scores are) for the group.

The county figures are the state’s own published county rows, not a sum of districts.

Who is counted

Reading: the grade 10 Reading MCA, taken by 10th graders. Math: the grade 11 Math MCA, taken by 11th graders. Science: the high school Science MCA, which students take once, in the school year they take life science or biology (any grade from 9 to 12); each year counts every high-school student who took it that year, whatever their grade.

From 2019 the number in each level also includes the students who took Minnesota’s alternate test for students with the most significant cognitive disabilities, between 1 and 2 of every 100 testers. The average score and the spread cover the MCA only. In 2018 the files count MCA takers only. A percentile compares a score with that year’s takers of the same test.

Important: the public data does not contain individual student scores, only these group summaries. So no tool can compute a true rank of one student against every other student. What we provide is a well-grounded estimate.

How the percentile is estimated

Minnesota publishes the exact scale-score range for each achievement level (e.g. for grade 11 Math, “Meets the Standards” is 1150-1163). Given a score, we:

identify which achievement level the score falls in;
count everyone in the lower levels as scoring below;
within the score's own level, spread that level's students along the group's curve (below) rather than evenly across the level's range. Students bunch up toward the middle of the scale, so an even spread would put too many of them out at the far ends of the lowest and highest levels.

That gives the percentile: the estimated share of students in the group who scored at or below the entered score. Checked against Minnesota’s published statewide score distributions for 2022 to 2024, this lands within about 2 percentile points of the true value for a typical score, usually slightly low: many students share each whole-number score, and the estimate counts few of the students tied with the entered score.

About the smooth curve

The bell-like curve on each chart is a truncated-normal distribution built from Minnesota’s own published average score and spread for the group. It's there to visualize the shape of the group's scores. The level counts set the headline percentile (steps above); the curve only decides where inside the student's own level the line falls.

A small group can report a very narrow spread. A curve narrower than one fifth of the statewide spread, which is about the size of the test's own measurement error, is drawn at that width instead, and inside the student's level the percentile then spreads that level's students evenly. The same even spread is used when all of a group's students sit in one level.

Why estimates are still useful: the achievement-level counts are real and complete for each group, and the average score and spread are Minnesota’s own published figures. The only assumption is how scores are distributed inside a level, a small and bounded range. Across a whole school, district, county, or the state, that assumption averages out well, so the comparison ("above/below average here vs. statewide") is reliable even though the exact percentile is approximate.

Cut scores

The score range for each level, by year, is on the score guides. Scores in the third and fourth levels meet the state standard.

Grade 11 Math uses the same ranges in every year shown: Does Not Meet 1102-1139, Partially Meets 1140-1149, Meets 1150-1163, Exceeds 1164-1195.
Grade 10 Reading used these ranges through 2025: Does Not Meet 1013-1039, Partially Meets 1040-1049, Meets 1050-1063, Exceeds 1064-1094. In 2026 Reading moved to a new test, the MCA-IV, with new ranges and new level names: Beginning 1001-1039, Intermediate 1040-1049, Meets 1050-1066, Advanced 1067-1099.
High school Science used these ranges through 2024: Does Not Meet 1001-1039, Partially Meets 1040-1049, Meets 1050-1062, Exceeds 1063-1099. In 2025 Science moved to the MCA-IV: Beginning 1001-1039, Intermediate 1040-1049, Meets 1050-1066, Advanced 1067-1099.

The ranges are from the Minnesota Department of Education’s cut score documents. The department replaces these documents when a test changes, so the earlier ranges come from archived copies, and the lowest and highest high school Science scores before 2025 come from the state’s published score tables (zero questions right is 1001, every question right is 1099). For 2022 to 2024 we also checked every range against the state’s published statewide score distributions.

The high-school progress report

The paid progress report puts every high-school test your child took in one table, with the percentile at each level from the school to the state, and charts each subject across the years.

Lines join only the same kind of comparison. Grade 10 Reading and grade 11 Math are taken by every student in that grade, so they continue the grades 3-8 Reading (shown as ELA) and Math lines. High school Science is taken once, in whatever grade a student takes life science, so it is compared with everyone who took it that year, whatever their grade, and shown as its own point.
Earlier years are compared statewide only. You can add your child’s grades 3-8 scores in the same subjects. The tool doesn’t know which middle school or district they attended, so those years are compared with every student in the state in that grade, not with this high school or its district.
The report opens on the statewide view, the one level with a result for every test.

Limitations to keep in mind

Percentiles are estimates, not official rankings. Treat a "62nd percentile" as "roughly the top 40%," not an exact standing.
Small schools have small counts, so their estimates are noisier.
Some school results are suppressed by the state (for privacy, small groups) and won't appear.
No statewide test was given in 2020 (COVID). In 2021 far fewer students took the tests than usual: about 40% fewer than in 2019 for grade 11 Math, 38% fewer for Science and 33% fewer for grade 10 Reading, so 2021 compares a smaller group that may not represent the whole state.
Reading from 2026 and Science from 2025 are on the newer MCA-IV, with different cut scores and level names, so a percentile from those years is not directly comparable with one from the earlier test.
Charter schools appear as their own districts in the state files and are included in the school, district, county and statewide comparisons.

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