Every number on this site traces back to data schools are federally required to report. Nothing is crowdsourced, estimated from news coverage, or guessed by an algorithm trained on reviews. Here is exactly what we do with that data — including what it can't tell you.
The most dangerous number in school data is a fake zero. A large school reporting zero incidents in every category, in a district where peers report plenty, is far more likely hiding problems than free of them. Those schools get a failing transparency grade and no safety score at all — flagged as suspected non-reporters instead of rewarded as "safe." Reporting completeness (A–F) is always shown next to the score so you know how much to trust it.
City, district, and state pages aggregate the raw serious-incident rates of their schools (never averaging percentiles, which is statistically invalid) and rank each geography against its own peers. A city is only ranked when at least 5 of its schools have trustworthy data — we show "why no ranking" honestly instead of ranking on thin evidence. City pages also show Zillow's typical home value, so safety can be weighed against price — see the Affordable & Safe guide.
It's a percentile from 0 to 100 — higher is safer. A 78 means this school's severity-weighted incident rate is lower than 78% of scored U.S. schools. It is not a letter grade or a pass/fail line.
The U.S. Department of Education's Civil Rights Data Collection (CRDC) — mandatory reporting by nearly every public school — plus NCES Common Core of Data for school directory and enrollment information, and Zillow's Home Value Index for the home-price cross-reference on city pages.
Usually because it reported implausibly little compared to similar schools. We never grade a suspected non-reporter as safe — hiding incidents should not earn a better score than honestly reporting them.
A separate A–F measure of how completely a school reported, independent of how many incidents it had. A school can have many reported incidents and an A for transparency — that data is more trustworthy than a suspicious row of zeros.
It's built for exactly that research — comparing schools, cities, and districts on the same footing, with home values alongside. But it reflects what schools reported in a federal collection year, not everything that happened. Treat it as one strong input next to school visits, local knowledge, and your own judgment — not a verdict.