How we estimate percentiles: Nebraska 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 Nebraska Education Profile of the Nebraska Department of Education, for the ACT that every Nebraska junior takes as the state test, in 2021 to 2025. For each school, school district and the state, and for each subject and year, these files give:

• the number of students tested and the number of students at each of Nebraska’s three levels, and
• the group’s average ACT score, which is where we center the curve.

Students who did not test. In its own reports, Nebraska counts some students who did not take the ACT at the lowest level, Developing (its rule for a student who did not test). Those students have no score, so we take them out: the number at Developing is reduced by the difference between the three level counts and the number tested. This removes about 3% of students statewide. On every school and district row the difference fits inside Developing and never exceeds the number Nebraska reports as not tested.

Hidden numbers. To protect small groups, Nebraska hides a level’s count when it is small. When only Developing is hidden, it is the number tested minus the other two levels; otherwise the school does not appear. Many small schools are missing for that reason; their students are still in the district and state results.

Who is counted

Nebraska gives the ACT with Writing to every student in their third year of high school (usually grade 11) as its state test. The ACT ELA score combines English, Reading and Writing. About 23,400 juniors took it in 2025. A percentile compares a score with the Nebraska public school juniors who took the ACT at school that spring. It is not the same as the national rank on an ACT score report, which compares with test takers across the country. Students who took Nebraska’s alternate assessment are not included.

How the percentile is estimated

Nebraska publishes the exact score range for each level (e.g. for ACT Math, On Track is 18-21). Given a score, we:

1. identify which 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 centered on the group’s published average ACT score, with its spread chosen so that its area within each level matches the level counts as closely as it can. 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.

ACT scores are whole numbers from 1 to 36, and Nebraska’s middle level is narrow (ACT ELA On Track is just 18 and 19). So a one-point change in an ACT score can move the percentile noticeably, and the curve is a smoothed picture of a score scale that really moves in steps.

Cut scores

Nebraska reports the ACT at three levels, set by the State Board of Education when the ACT became the state test in 2017: Developing, On Track and ACT Benchmark. On Track and above count as proficient.

• ACT ELA: Developing 1-17, On Track 18-19, ACT Benchmark 20-36
• ACT Math: Developing 1-17, On Track 18-21, ACT Benchmark 22-36
• ACT Science: Developing 1-18, On Track 19-22, ACT Benchmark 23-36

These come from the Nebraska Department of Education’s 2018-19 data definitions, its 2024 “ACT Performance Level Ranges” and its 2024 preface to the ACT performance level descriptors, which all print the same table. 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 ACT is taken by the whole grade 11 class, so ACT ELA and ACT Math continue the grades 3-8 ELA and math lines. The ACT uses a different scale from the grades 3-8 tests, but each point is a percentile among that year’s students in that grade, so the points compare. ACT Science has no grades 3-8 line of its own here.
• 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, and many are hidden.
• Not included: 2020 (no test, COVID); 2018 and 2019, when Nebraska published only the share of students at each level, including students who did not test, without the number tested, so those students can’t be taken out; and 2026, which Nebraska has not released yet.
• Nebraska is compared at the school, district and state levels.

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