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How we estimate percentiles: Mississippi 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 yearly MAAP results files of the Mississippi Department of Education, for its four high-school end-of-course tests: English II and Algebra I (2018, 2019 and 2021 to 2026), Biology (2019 and 2021 to 2026) and US History (2021 to 2025). For each school, school district and the state, and for each test and year, these files give:
- the number of students tested, the share of students in each of the five performance levels, and
- the group’s average scale score, which is where we center the curve. The 2018 files have no average, so for 2018 it is estimated from the level shares.
Hidden numbers. Mississippi does not publish results for very small groups, so a few small schools are missing. The schools shown hold more than 99% of each year’s test takers. The statewide row is Mississippi’s own statewide total.
Who is counted
English II, Algebra I, Biology and US History are end-of-course tests: students take each one at the end of the course, whatever their grade. So a percentile compares a score with that year’s Mississippi public school students in the course, not with every student of the same age. Algebra I includes middle-school students who took the course early (in 2025, at least 1,300 of about 31,000 testers were at middle or junior high schools), counted at their own school.
About 30,000 students take each test each year (in 2026: English II 29,000, Algebra I 30,000, Biology 30,000; in 2025, US History 31,000).
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
Mississippi publishes the exact score range for each performance level (e.g. for Algebra I, “Passing” is 1050-1064). Given a score, we:
- identify which performance 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 fitted 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.
About the smooth curve
The bell-like curve on each chart is a truncated-normal distribution centered on the group’s published average score, with its spread chosen so that its area within each performance level matches the published level shares as closely as it can. It's there to visualize the shape of the group's scores. The level shares set the headline percentile (steps above); the curve only decides where inside the student's own level the line falls.
Why estimates are still useful: the share of students in each performance level, the number tested and the average score are Mississippi’s own published numbers for each group (2018’s average is estimated). The only assumption is how scores are distributed inside a level, a small and bounded range. Across a whole school, district, 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
Each test has five levels: Minimal, Basic, Passing, Proficient and Advanced. Mississippi’s passing score is 1050 (the start of Passing) on every one of these tests.
- English II: 1001-1036, 1037-1049, 1050-1064, 1065-1080, 1081-1099
- Algebra I: 1001-1038, 1039-1049, 1050-1064, 1065-1087, 1088-1099
- Biology: 1000-1037, 1038-1049, 1050-1064, 1065-1094, 1095-1180
- US History: 1000-1036, 1037-1049, 1050-1064, 1065-1088, 1089-1150
These come from the Mississippi Department of Education’s “MAAP Performance Level Scale Score Ranges” (revised September 2025), which says the ranges apply to all MAAP administrations, and its “Mississippi Science and History Results”, which prints the Biology and US History table. Biology’s scale was set in summer 2019 and US History’s in summer 2021. The score range for each level, by year, is on the score guides.
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.
- Each course test is its own point. English II, Algebra I, Biology and US History are taken by the students in each course that year, a different group for each course, so a line between them would not show real progress.
- Earlier years are compared statewide only. You can add your child’s grades 3-8 scores. 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.
- Not included: 2020 (no test, COVID); Biology in 2018 and US History in 2018 and 2019, which were on older scales whose score ranges we have not found; and US History 2026, which Mississippi has not published.
- Mississippi is compared at the school, district and state levels.
This site stores nothing you type. Scores are used only in your browser to draw your charts.
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