121 School Index methodology — v2

The 121 School Index summarizes individual-school evidence; it is not an official school rating and not an enrollment guarantee.

Academic change has 45% weight, academic performance 30%, college/career readiness 20% for high schools, and attendance 5%. Missing components are reweighted only when at least 60% of eligible weight is observed.

• Academic change: published year-over-year change in California distance-from-standard status for English language arts and mathematics. It is not a longitudinal growth model.
• Academic performance: published distance-from-standard status for English language arts and mathematics.
• College/career readiness: published prepared percentage for eligible high-school cohorts.
• Attendance: published chronic-absence evidence, oriented so lower absence is stronger.

Percentiles compare schools only within the same school level and only when the comparable cohort and published sample meet v2 minimums.

Alternative, continuation, special-education, adult, primarily virtual, closed, and otherwise non-comparable records do not receive a numeric indicator. Every record shows coverage, confidence, school year, and source vintage.

Subgroup missingness and score distributions are release checks, not public subgroup ratings. A gap above the review threshold blocks release unless a release-bound independent adjudication records approve_with_disclosure; reject and methodology_change_required decisions remain blocking.

• Minimum component sample: 20 students.
• Minimum comparison cohort: 20 schools.
• Minimum observed eligible weight: 60%.

Source bytes are stored as immutable, checksummed release artifacts. Each public record links to the exact release and source vintage.

• California Department of Education Public Schools and Accountability Dashboard files — California public data terms and source attribution apply.
• National Center for Education Statistics Common Core of Data — U.S. Department of Education public data terms and attribution apply.
• District or county attendance-boundary sources are used only when their authority, vintage, and feature identifiers are recorded.

The registered California Dashboard chronic-absence indicator covers TK–8, so the attendance component is generally absent for high schools and the observed high-school components are reweighted with disclosed coverage.

Published indicators do not measure every aspect of a school and should not be used alone for enrollment, housing, or family decisions. Attendance boundaries, choice programs, transfers, charters, magnets, and capacity can change independently.

Registered sources are checked monthly. A candidate school release is normally rebuilt annually when official source versions change, with correction releases when verified source errors require them.

Version v2 is permanent. Later methodology changes receive a new versioned URL; this page is not silently rewritten into a different method.

• Corrections require a new checksummed release and validation report.
• Previously approved releases remain available for rollback and audit.

• California Department of Education data and reports
• National Center for Education Statistics

Machine-readable document: /methodology/121-school-index/v2.json.