How we estimate percentiles: Rhode Island 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 Rhode Island Department of Education’s Assessment Data Portal, for its high-school tests: the PSAT 10 in grade 10 and the School Day SAT in grade 11 (each with a Reading and Writing section and a Math section), in 2021 to 2026, and the NGSA science test in grade 11, in 2019 and 2021 to 2026. For each school, district and the state, and for each test and year, the portal gives:

the number of students tested and the percentage in each of the four achievement levels, to one decimal, and
the group’s average scale score, which sets the center of its bell curve.

Who is counted

Rhode Island gives the PSAT 10 to its grade 10 students and the SAT, at school on its spring School Day, to its grade 11 students, along with the NGSA science test. A percentile compares a score with that year’s Rhode Island public school students who took the same test, by the school where they tested: about 9,700 students in grade 10 and 9,800 in grade 11 in 2026. An SAT or PSAT percentile here is not the same as the national percentile on a College Board score report, which compares with test takers across the country.

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

Rhode Island publishes the exact score range for each achievement level (e.g. for SAT Math, Meeting Expectations is 530-640). 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 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 fitted so that its area within each achievement level matches the published percentages. 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.

Why estimates are still useful: the number tested, the percentage at each level and the average score are Rhode Island’s own published numbers for each group. 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 four levels: Not Meeting, Partially Meeting, Meeting and Exceeding Expectations (for the NGSA: Beginning to Meet, Approaching, Meeting and Exceeding Expectations). Meeting and above count as proficient. The SAT and PSAT 10 report each section in steps of 10.

SAT Reading and Writing: 200-410, 420-470, 480-620, 630-800
SAT Math: 200-410, 420-520, 530-640, 650-800
PSAT 10 Reading and Writing: 160-360, 370-420, 430-580, 590-760
PSAT 10 Math: 160-380, 390-470, 480-590, 600-760
NGSA grade 11 science: 1-35, 36-59, 60-70, 71-120

The PSAT 10 and SAT ranges come from the Department’s PSAT 10 and SAT Achievement Level Descriptors (revised August 2021), which say they are adapted from the 2016 multi-state SAT standard setting; the SAT ranges are the same ones Connecticut, Delaware and New Hampshire use. The NGSA ranges come from the NGSA technical report; they were set in August 2019. 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 PSAT 10 and SAT are taken by the whole grade, so each section forms one line from grade 10 to grade 11, continuing the grades 3-8 ELA and math lines. Science continues the grade 5 and grade 8 NGSA tests. The scales differ, but each point is a percentile among that year’s students in that grade, so the points compare.
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); the PSAT 10 and SAT in 2018 and 2019, because the Department’s table of score ranges dates from 2021 and we have not found one from those years.
Rhode Island is compared at the school, district and state levels.

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