majiayu000 MAP Growth 2025 Norms
Overview
Official 2025 NWEA MAP Growth normative data derived from 116M+ test events across 13.8M students in 29,720 US public schools (2022-2024). Provides achievement and growth norms for student and school-level comparisons.
Coverage
| Subject | Student Grades | School Grades |
|---|---|---|
| Mathematics | K-12 | K-12 |
| Reading | K-12 | K-12 |
| Language Usage | 2-11 | 2-11 |
| Science | 2-10 | 2-10 |
Key Concepts
Achievement Norms
Cross-sectional RIT performance at specific time points. Answers: "How does this score compare to peers?"
Growth Norms
Change between two assessments. Conditional on starting RIT score. Answers: "Is this growth typical for students who started at this level?"
Seasonal Timing (Weeks from District Start)
- Fall: Week 4 (0-12 weeks)
- Winter: Week 20 (13-28 weeks)
- Spring: Week 32 (29+ weeks)
Percentile Calculations
Achievement Percentile
function calculateAchievementPercentile(
ritScore: number,
mean: number,
sd: number
): number {
const z = (ritScore - mean) / sd;
// Standard normal CDF approximation
const p = 0.5 * (1 + Math.sign(z) * Math.sqrt(1 - Math.exp(-2 * z * z / Math.PI)));
return Math.round(p * 100);
}
Growth Percentile (Conditional) - Technical Manual Section 3.3.3
Growth percentiles are conditional on starting RIT. Higher starting scores have lower expected growth (regression to mean effect).
function calculateGrowthPercentile(
startRit: number,
endRit: number,
normData: GrowthNormData
): number {
const observedGrowth = endRit - startRit;
// Conditional mean adjusted for starting RIT (Section 3.3.2)
const expectedGrowth = normData.meanGrowth +
normData.regressionCoeff * (startRit - normData.startMean);
const z = (observedGrowth - expectedGrowth) / normData.conditionalSD;
return normalCDF(z) * 100;
}
→ See: lib/map/conditional-growth.ts for full implementation
Reference Files
See references/ for complete norm tables:
- achievement-norms.md: Mean and SD by grade/subject/season (Student & School)
- achievement-percentiles.md: RIT-to-percentile lookup tables
- growth-norms.md: Mean and SD for within-year and between-year growth
Quick Lookup Examples
Student Achievement (Reading, G4, Spring)
- Mean: 202.09
- SD: 17.74
- A RIT of 210 → ~68th percentile
Student Achievement (Language Usage, G3, Fall)
- Mean: 184.42
- SD: 17.37
- A RIT of 195 → ~73rd percentile
Integration Notes
- Always use conditional growth norms - Marginal growth (ignoring starting RIT) produces misleading percentiles
- School norms have smaller SD - Aggregation reduces variance
- Week timing matters - Norms assume standard seasonal weeks (4/20/32)
- EISA concordance applied - 2025 norms aligned to enhanced item-selection algorithm scores