How we estimate percentiles

Plain-English 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 official public test-results files - the NYC Department of Education's InfoHub for district schools, plus New York State (NYSED) report-card data for charter schools and the statewide comparison (New York State ELA, Math & Science exams, grades 3-8, 2018-2025). These files report, for each school / grade / year:

the number of students tested and their mean scale score, and
how many students landed in each performance level (Level 1, 2, 3, 4).

Important: the public data does not contain individual student scores - only these group summaries. So no tool can compute a true rank of one child against every other child. What we provide is a well-grounded estimate.

How the percentile is estimated

New York publishes the exact scale-score range for each performance level (e.g. for Grade 3 Math in 2024, Level 3 is 450-486). Given your child's 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, use linear interpolation across that level's count - i.e. assume scores are spread evenly across the level's range.

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 real reported counts, anchored to the group's reported mean. It's there to visualize the shape of the group's scores. The headline percentile comes from the counts (step above), not from the curve.

Why estimates are still useful: the performance-level counts are real and complete for each group. The only assumption is how scores are distributed inside a level - a small, bounded range. Across a whole school, district, borough, or the city, that assumption averages out well, so the comparison ("above/below average here vs. city-wide") is reliable even though the exact percentile is approximate.

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.
Some school/grade cells are suppressed by the DOE (for privacy) and won't appear.
New York rescaled the exams over time; we always compare a score against the ranges for the same year you select.
Charter-school results come from NYSED's report-card data (the DOE's InfoHub files omit charters). Charter test-takers are included in the school, district, borough and city comparisons, so those baselines reflect all NYC public-school students.

This site stores nothing you type. Scores are used only in your browser to draw your charts.

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