How the Success Index (US) works
A transparent, reproducible way to compare every American school using only official data. No surveys, no paid placements, no black box.
Data sources
The US Success Index covers every regular public and charter school in the NCES Common Core of Data. It combines state-assessment proficiency in reading and math (EDFacts, all students), the share of students eligible for free or reduced-price lunch as a measure of community advantage, and the student–teacher ratio. Each component is a percentile against schools of the same level (elementary, middle, high) across the whole country; state and district ranks are shown on every profile.
- Urban Institute Education Data Portal (NCES CCD, EDFacts) (ODC-BY / public domain)
- NCES Common Core of Data (Public domain)
The current dataset covers 89,160 schools, of which 84,718 receive a score and 82,580 are ranked. Data was retrieved on 8 October 2026.
The components
Each school is compared only with schools of the same type across United States. For each component we convert the raw value to a percentile within that type, then combine the percentiles with these weights:
| Component | Weight | Raw measure | Why it matters |
|---|---|---|---|
| Math proficiency | 30% | Math proficiency | Share of tested students proficient or above on the state math assessment. |
| Reading proficiency | 30% | Reading proficiency | Share of tested students proficient or above on the state reading/language arts assessment. |
| Community advantage (fewer free/reduced-price lunch) | 25% | Free/reduced-price lunch (lower is better) | Share of students eligible for free or reduced-price lunch; lower indicates a more advantaged community. |
| Students per teacher | 15% | Students per teacher (lower is better) | Enrollment divided by full-time-equivalent teachers. |
Adjustments
- Missing components are left out and the remaining weights are rescaled, so a school is never penalised for data that is not published for its type.
- Small schools: components marked as size-sensitive are shrunk toward the median for schools under 300 students, and schools with fewer than 60 students are scored but not ranked.
- Excluded types: Other are listed but not scored.
- Required data: a school needs a published Enrollment to be scored.
Bands and ranks
The combined score is placed on a 0–100 scale and labelled by percentile within school type: Top 5%, Top 10%, Top 25%, Top 50% or Lower 50%. Ranks are computed nationally, within each state and within each school district, always within school type.
Known limitations
- States set their own assessments and proficiency cut scores, so proficiency rates are most comparable within a state. Use the state rankings for like-for-like comparisons.
- EDFacts reports proficiency in ranges for small schools; we use the midpoint, and schools with fewer than 30 tested students are excluded from results-based lists.
- Private schools are not covered by the Common Core of Data and are not listed.
Attribution
School directory, enrollment, lunch-program and staffing data: National Center for Education Statistics, Common Core of Data, accessed through the Urban Institute Education Data Portal. Proficiency: U.S. Department of Education EDFacts. Public domain. The Success Index is produced by Success Tutoring and is not endorsed by NCES or the Department of Education.
Frequently asked questions
Is the Success Index (US) a measure of school quality?
No. It summarises published data about a school community and, where available, attainment. These correlate with academic results but do not measure teaching quality, wellbeing or culture.
Why are small schools not ranked?
Schools with fewer than 60 students have growth and attainment figures that swing dramatically with a handful of enrolments. They receive a score on their profile page but are excluded from ranking tables.
How often is it updated?
Automatically whenever the source agencies publish new data, plus whenever we improve the methodology. The data year (2025) is shown on every page.
Can a school pay to improve its ranking?
No. Success Tutoring accepts no payment from schools, and the index is computed mechanically from official data by open-source code.