How we estimate percentiles: Texas 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 Texas Education Agency’s public results for the five STAAR end-of-course (EOC) tests a Texas diploma requires: Algebra I, English I, English II, Biology and US History, for 2018, 2019 and 2021 to 2026. For 2018 to 2023 the source is TEA’s STAAR Aggregate Data files; for 2024 to 2026 it is the campus summaries in the Texas Education Research Portal. For each campus and each test and year, these files report:

the number of students tested and the number at each of the four performance levels; and
the campus’s average scale score, a real average computed by TEA, not an estimate.

District, county and statewide results add up the campuses.

Who is counted

These counts are the students who took each test in the spring (April or May), first-time testers and retesters alike. Students who tested in December or June are not included: TEA reports those administrations separately. For 2022 Algebra I, the statewide totals here match TEA’s own summary report exactly (473,672 students tested). For 2019 and 2021 to 2026, the statewide share at each level is within 1 point of the spring results TEA publishes for every test.

A course test is taken by whoever is in the course that year, so each test has its own group: in 2026 about 448,000 students took Algebra I, 465,000 English I, 447,000 English II, 417,000 Biology and 390,000 US History. Middle-school students who take Algebra I early are counted at their middle school (about one Algebra I tester in five is at a campus with no English I or II testers). A percentile compares a score with that spring’s takers of the same test, not with every student of the same age, and an Algebra I percentile says nothing about Biology.

Campuses with fewer than 5 testers on a test have their results hidden by TEA and are left out; they hold about 0.1% of the students.

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

Each STAAR end-of-course test has a published scale-score range for each performance level (for Biology in 2023, Meets Grade Level is 4000 to 4530). 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. The lowest and highest levels are very wide on these tests (Algebra I’s Did Not Meet runs from 1500 to 3549 in 2023), and an even spread would put far too many students out at their far ends.

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 real average score, with its spread fitted so that its area within each level matches the level counts. The level counts set the headline percentile (steps above); the curve only decides where inside the student’s own level the line falls.

When a group’s students all sit in one or two levels, the counts can’t say how spread out their scores are. A curve that comes out too narrow is drawn no narrower than one fifth of the statewide spread, and inside the student’s level the percentile spreads that level’s students evenly instead.

How well it works: a check against TEA’s own tables

Texas is one of the few states that publishes the real statewide distribution of scores: a percentile for every possible score (2018, 2019 and 2023 to 2026) and the full count of students at every score (2021, and Algebra I in 2022). We compare the statewide percentile this tool shows with TEA’s at every score TEA prints:

the share of students below each performance level matches TEA’s tables to within 1 point, and to within 0.01 points where TEA prints the full counts;
across 1,784 scores the tool’s statewide percentile is off by about 1 point in a typical case, and by 0.2 points too low on average;
from Approaches Grade Level up, no score is off by more than 4 points. The largest gaps, up to about 8 points (2025), are at the very bottom of Algebra I (TEA’s 2nd to 8th percentiles), where fewer students score than a bell curve expects. Spreading students evenly inside each level, the simpler method, misses by as much as 10 to 26 points at the ends of the scale.

There is no TEA table to compare with for US History in 2019 or for English I, English II, Biology and US History in 2022 (TEA’s 2022 table is a scanned image that can’t be read reliably).

Why estimates are still useful: the performance-level counts and the campus averages are TEA’s own. The only assumption is how scores are distributed inside a level, and the statewide check above shows how small that error is. Across a whole campus, district, or the state, the comparison ("above/below average here vs. statewide") is reliable even though the exact percentile is approximate.

Cut scores

Every STAAR end-of-course test has four levels: Did Not Meet Grade Level, Approaches Grade Level, Meets Grade Level and Masters Grade Level. Approaches is the passing standard a student needs to graduate. Meets Grade Level starts at 4000 on every test, and Approaches starts at 3550 (3775 on English I and II).

STAAR was redesigned in spring 2023 and the scale was reset, so Masters starts at a different score from 2023 on: Algebra I 4333 before 2023 and 4345 from 2023, English I 4691 and 4606, English II 4831 and 4734, Biology 4576 and 4531, US History 4440 and 4424. Scale scores are not comparable across that change; percentiles are, since they always compare students within one test and year.

Biology was redesigned again in spring 2026 to cover Texas’s revised science standards. Approaches (3550) and Meets (4000) did not move, but Masters starts at 4570 from 2026 (4531 in 2023 to 2025).

The cuts come from TEA’s Technical Digest (2018-2019 and 2020-2021 editions, chapter 4, which agree) for 2018 to 2022, from the 2023 STAAR EOC performance standards in Texas Administrative Code, 19 TAC §101.3041, for 2023, and from the cut scores TEA prints under each spring’s raw score conversion tables for 2024 to 2026. The lowest and highest possible score each year come from TEA’s statewide score tables for that spring. 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 campus to the state, and charts each subject across the years.

Each course exam is its own point. Every Texas end-of-course test is taken by the students in that course that year, a different group for each course, so the report does not join them with a line.
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 campuses have small counts, so their estimates are noisier.
Not included: 2020 (no test, COVID); December and June retests; and Algebra II and English III, which are optional and not in these files.
Texas is compared at the campus, district, county and state levels.

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