How we estimate percentiles: Oklahoma 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 Oklahoma State Department of Education’s report-card data for its grade 11 tests: ELA and math in 2018, 2019 and 2022 to 2025, science in 2022 to 2025, and US History in 2022 and 2023. For each school, school district and the state, and for each test and year, these files give:

• the percentage of students in each of the four performance levels, rounded to whole numbers. The files do not give the number of students tested, so the comparisons work from the percentages; and
• from those percentages, an estimated average score: the center of the bell curve that best matches the share of students below each level’s cut score.

A few groups have no published percentages and are left out.

Who is counted

Oklahoma tests its grade 11 students with its College- and Career-Readiness Assessment. For ELA and math, that is the ACT or the SAT, whichever the school district chooses, taken at school in the spring; Oklahoma converts each score to its own 200-399 scale, so ACT and SAT takers are compared together. Science and US History are Oklahoma’s own tests on the same 200-399 scale. A percentile compares a score with that year’s Oklahoma public school students in grade 11, by the school where they tested.

From an ACT or SAT score to Oklahoma’s scale

The tool takes the score on Oklahoma’s 200-399 scale. These tables from the State Department of Education give the Oklahoma score for each ACT or SAT score; the SAT column is the SAT score that matches each ACT score.

• Math uses the ACT Math score (1-36) or the SAT Math score (200-800) from your child’s report. The box above the form on the tool page converts it for you. The table does not list every SAT Math score; for one it skips, your child’s school can give the exact Oklahoma score.
• ELA uses Oklahoma’s own weighted ELA score, which is not printed on an ACT or SAT report. For the ACT it is 2 × (0.425 × Reading + 0.425 × English + 0.15 × Writing); for the SAT, 0.85 × Evidence-Based Reading and Writing + 0.15 × Essay. Schools can see it in the state’s reporting system, so your child’s school can give you the Oklahoma ELA score.

How the percentile is estimated

Oklahoma publishes the exact score range for each performance level (e.g. for grade 11 Math, Proficient is 300-338). Given a score, we:

1. identify which performance level the score falls in;
2. count everyone in the lower levels as scoring below;
3. 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 fitted so that its area within each performance level matches the published percentages, centered on that estimated average score. It's there to visualize the shape of the group's scores. The percentages set the headline percentile (steps above); the curve only decides where inside the student's own level the line falls.

ELA and math scores come from ACT and SAT scores, so only certain Oklahoma scores occur (an ACT Math score of 20 is 297 and 21 is 300). The curve is a smoothed picture of a scale that really moves in steps.

Cut scores

Each test has four levels: Below Basic, Basic, Proficient and Advanced. Proficient and above count as proficient.

• Grade 11 ELA: 200-257, 261-297, 300-340, 344-399
• Grade 11 Math: 200-246, 258-297, 300-338, 346-399
• Grade 11 Science: 200-277, 278-299, 300-326, 327-399
• Grade 11 US History: 200-289, 290-299, 300-329, 330-399

The gaps in ELA and math are real: no ACT or SAT score converts to a score inside them. These ranges come from the State Department of Education’s “OSTP and CCRA Performance Level Cut-Points” tables and its CCRA look-up tables (spring 2022, school year 2024, and the current edition). The ELA and math levels were set in 2018, when Oklahoma began using the ACT and SAT as its high-school test. Oklahoma changed its grades 3-8 cut scores for 2024 only; its 2024 table has no new grade 11 ELA or math ranges, and the grade 11 results show no break that year while grades 3-8 jump. 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.

• One line per subject. The grade 11 tests are taken by the whole class, so ELA, math and science continue the grades 3-8 lines in the same subject (science is tested in grades 5 and 8). The scales differ, but each point is a percentile among that year’s students in that grade, so the points compare. US History has no grades 3-8 line of its own.
• 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.
• The files give whole-number percentages and no student counts, so a small school’s results are rounded and noisier, and the tool can’t show how many students a comparison covers.
• Not included: 2020 and 2021 (no results published, COVID); science in 2019, because every copy of the science cut scores we found dates from 2022 or later; US History in 2024 and 2025, when the school and district percentages stop adding up to 100 (some fall short by 5 points or more) and the files do not say why; and 2026, which Oklahoma has not posted yet.
• Oklahoma is compared at the school, district and state levels.

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