West Mercer Elementary
Mercer Island, WA · Grades K–5
Seattle-Tacoma-Bellevue, WA
NeighborhoodDecoded Rank
All factors combined
WA statewide rating — the rank below is this school's statewide position
Top 15% decoded
#106 of 1502
Washington schools
#65 · Seattle-Tacoma-Bellevue metro
Achievement Rank
Raw test performance
Top 5% achievement
#21 of 1502
Washington schools
#20 · Seattle-Tacoma-Bellevue metro
★Strong by Both Measures
Raw scores are high here, and the school remains strong for its context; students tend to gain ground relative to peers over time.
Data confidence:High438 students tested 7 years99% participation
Confidence is computed from sample size, year coverage, and participation rate. Higher confidence means the rank shift is stable across years and not driven by a single small cohort.
- Tested students: total students with valid scores across all reported years.
- Years of data: number of school years included. More years smooths year-to-year noise.
- Participation: share of enrolled students who took the assessment. Low participation can bias scores.
What's driving this rank
Decoded Rank: #106 of 1502
in Washington schools
Raw test scores rank this school #21, but families here have higher-than-average income and educational attainment, so the expected score is also high. After accounting for context, this school performs about as predicted — the Decoded Rank is #106.
Each component below is scored on a 0–100 within-metro scale. A qualitative band summarizes where the school lands.
- StrongPerforms above what its context predictsCounts for 39% of the rank
After accounting for income and demographics, does this school beat what the data would predict?
- StrongStudents gain ground year over yearCounts for 33% of the rank
Are kids at this school learning faster than typical for the metro?
- Below averageEquity within the schoolCounts for 17% of the rank
Are students clustered at similar levels, or split between top and bottom?
- StrongMost students were testedCounts for 11% of the rank
Was the rank computed against a representative share of the school's students?
Show the numbersFor the methodology-curious
Each component is converted to a 0–100 within-metro percentile (100 = top of the metro). "Contribution" is the percentile-points the component adds to (or subtracts from) the metro median before the schools are re-ranked into the composite.
| Component | Weight | Percentile | Contribution |
|---|---|---|---|
| Performs above what its context predicts | 39% | 89 | +15.3 |
| Students gain ground year over year | 33% | 94 | +14.7 |
| Equity within the school | 17% | 33 | -2.9 |
| Most students were tested | 11% | 99 | +5.4 |
Why trust this?- Public data sources
- Context-adjusted model
- Confidence shown
- Methodology published
This score uses state assessment data, NCES enrollment data, and Census ACS 5-year neighborhood data. The Decoded Rank adjusts for school context — student demographics, ELL/SPED service rates, and the socioeconomic profile of the surrounding tract — and shows how the school performs relative to expectation, not in absolute terms.
SchoolDecoder is one signal, not a verdict. Decoded Rank is a context-adjusted residual, not a causal claim about teaching quality. See full methodology →
Strongest Subjects (Decoded)
Decoded rank first; achievement rank in parentheses. Sorted by decoded rank, best first. Science is shown for reference only and is not part of any rank, tier, or composite.
Science
2023 proficiency87.7%meeting standard
Tested gradeGrade 5
81 tested
202285.7%202387.7%
Shown for reference only — science is not part of any rank.
All Rankings
How this school ranks across the metro, state, and among demographic peers.
| Scope | Achievement | Decoded | Shift |
|---|---|---|---|
| WA (1502 schools) | #21 | #106 | |
| Seattle-Tacoma-Bellevue, WA (674 schools) | #20 | #65 | |
| Among similar schools (6 peers) | #3 | #3 |
Resource context
School inputs, not ranking points
These fields describe the school and surrounding neighborhood. They help readers interpret the page, but this is not a dollar-by-dollar or ratio-by-ratio scorecard and the fields here are not components of the Decoded Rank.
- Enrollment
- 422
- Free/reduced-price lunch
- 6.6%
- Student-teacher ratio
- 18.3:1
- Locale
- Suburb, large
- School type
- Regular public school
- Enrollment model
- Neighborhood attendance area
- Neighborhood median income
- $250,001ACS tract proxy
- Neighborhood poverty
- 1.6%ACS tract proxy
- SES index
- 98.6
- Assessment data year
- 2023
- CCD year
- 2022
- ACS vintage
- 2020-2024
Within Mercer Island School District: #3 of 5.Middle quintile in district. View district
Performance Spread
How students are distributed across the four state-assessment proficiency levels — L1: below standard, L2: approaching, L3: meets (proficient), L4: exceeds. This describes the shape of results at the school, not their height.
Students at this school cluster closely on the proficiency ladder.
- Level 1 — Below standard4%
- Level 2 — Approaching standard10%
- Level 3 — Meets standard (proficient)20%
- Level 4 — Exceeds standard65%
Performance Spread measures how evenly students are distributed across the L1..L4 proficiency ladder, treating the levels as an ordered scale (L1=1, L2=2, L3=3, L4=4) and weighting each by its student share. A school where most students cluster at one level has a TIGHT spread; a school split between the bottom and top has a WIDE or BIMODAL spread. Bimodal fires only when BOTH tails are non-trivial AND the middle is relatively hollow (pct_L1 ≥ 15, pct_L4 ≥ 25, pct_L2 + pct_L3 ≤ 60). It describes shape — NOT how high the school's scores are. Methodology
Nearby Schools
Sorted by distance. Both rank columns shown so you can compare quickly.
- Northwood Elementary School0.4 mi
- Mercer Island High School0.6 mi
- Island Park Elementary1.3 mi
- Enatai Elementary School2.0 mi
- Islander Middle School2.4 mi
| School | Rating | Achievement | Decoded | Shift | Story | Confidence |
|---|---|---|---|---|---|---|
| Northwood Elementary School | #80 | #111 | ★Strong by Both Measures | High | ||
| Mercer Island High School | #1 | #5HS | HS outcome | HS pool | ||
| Island Park Elementary | #8 | #29 | ★Strong by Both Measures | High | ||
| Enatai Elementary School | #160 | #239 | High Scores, Context Matters | High | ||
| Islander Middle School | #91 | #83 | ★Strong by Both Measures | High |
Similar Schools
Schools with comparable demographics, income, and size. Both rank columns shown for direct comparison.
| School | Rating | Achievement | Decoded | Shift | Story | Confidence |
|---|---|---|---|---|---|---|
| Cascade Ridge Elementary | #9 | #10 | ★Strong by Both Measures | High | ||
| Sunrise Elementary | #6 | #17 | ★Strong by Both Measures | High | ||
| Carl Sandburg Elementary | #87 | #139 | ★Strong by Both Measures | High | ||
| Lynden Academy | Rank withheld | |||||
| Thornton Creek Elementary School | Rank withheld | |||||
Historical Ranks
Year-by-year decoded and achievement ranks. Pandemic-affected years are excluded — we don't interpolate scores across the gap.
| Year | Achievement | Decoded | Shift |
|---|---|---|---|
| 2023 | #20 | #65 |
Note: assessment transitions (where a state changes its test) are footnoted on the methodology page; trends are not computed across breakpoints.
Trajectory
Not used in the Decoded Rank — shown for context only.
Not enough years yet
Trajectory will appear once we have two or more years of rankings for this school.
How this works: we fit a linear trend across the available years of Decoded percentile, then bucket the slope into a direction. Wide confidence intervals (uncertain trends) collapse to Holding steady. See the methodology page for thresholds.
Cohort Progression
Kids who started 3rd grade here in 2022 gained 16 proficiency points by 4th grade — gaining, versus a metro median of about 0/yr.
Based on 12 cohorts across math + ELA.
Learning rate: +3.2 proficiency points/yr (95% CI -5.1 to 11.5)
Medium confidence
| Cohort | 2015 | 2016 | 2017 | 2018 | 2019 | 2022 | 2023 | Slope |
|---|---|---|---|---|---|---|---|---|
| ELA · started 5th in 2015 | G5 330 | — | ||||||
| ELA · started 4th in 2015 | G4 341 | G5 353 | +11.5 | |||||
| ELA · started 3rd in 2015 | G3 342 | G4 341 | G5 352 | +5.2 | ||||
| ELA · started 3rd in 2016 | G3 329 | G4 351 | G5 336 | +3.3 | ||||
| ELA · started 3rd in 2017 | G3 336 | G4 342 | G5 351 | +7.7 | ||||
| ELA · started 4th in 2019 | G4 356 | — | ||||||
| ELA · started 3rd in 2019 | G3 334 | — | ||||||
| ELA · started 5th in 2022 | G5 353 | — | ||||||
| ELA · started 4th in 2022 | G4 358 | G5 340 | -18.8 | |||||
| ELA · started 3rd in 2022 | G3 329 | G4 345 | +16.3 | |||||
| ELA · started 3rd in 2023 | G3 362 | — | ||||||
| Math · started 5th in 2015 | G5 329 | — | ||||||
| Math · started 4th in 2015 | G4 332 | G5 330 | -2.0 | |||||
| Math · started 3rd in 2015 | G3 328 | G4 328 | G5 340 | +6.0 | ||||
| Math · started 3rd in 2016 | G3 318 | G4 348 | G5 339 | +10.5 | ||||
| Math · started 3rd in 2017 | G3 354 | G4 347 | G5 335 | -9.4 | ||||
| Math · started 4th in 2019 | G4 352 | — | ||||||
| Math · started 3rd in 2019 | G3 327 | — | ||||||
| Math · started 5th in 2022 | G5 329 | — | ||||||
| Math · started 4th in 2022 | G4 360 | G5 340 | -20.7 | |||||
| Math · started 3rd in 2022 | G3 330 | G4 358 | +27.4 | |||||
| Math · started 3rd in 2023 | G3 342 | — |
How this works: we follow each grade-cohort across years through the school (3rd graders in 2023 are 4th graders in 2024, etc.) and fit a linear slope on a 100–400 proficiency-points scale built from the state assessment's four levels (L1=1, L2=2, L3=3, L4=4, weighted by student share). This is the same construction Stanford SEDA uses (edopportunity.org/methods); it's not student-level tracking — we measure the school's cohort, not individuals. See the methodology page for thresholds.
Student Growth (Washington)
Student growth percentile: the typical student here grew faster than 63% of Washington students with similar score histories.
Median Student Growth Percentile (SGP), as published by Washington's Office of Superintendent of Public Instruction. 50 is exactly typical for the state. Based on 5 years of data.
| Year | Math SGP | ELA SGP | Students (math / ELA) |
|---|---|---|---|
| 2016 | 56 | 59 | 240 / 241 |
| 2017 | 73 | 59 | 183 / 182 |
| 2018 | 63 | 57 | 202 / 199 |
| 2019 | 62 | 58 | 183 / 182 |
| 2023 | 63 | 64 | 137 / 136 |
Washington did not administer statewide tests during 2020–2022, so those years are absent — a gap in the data, not a score of zero.
How this works: a Student Growth Percentile compares a student's score change to other Washington students who started at a similar place, so it measures growth independent of where a student began. We show Washington's published medians; Oregon does not publish student growth percentiles, so this panel never appears on Oregon schools. See the methodology page for how growth enters the Decoded Rank.
Evidence & technical detailClick to expand
School Alpha
School Alpha is the residual between actual and expected performance once school context is held constant. It is a context-adjusted estimate, not a causal claim about teaching quality. Its reliability shows up on the page as the confidence label and the rank interval, not as a standalone statistic.
SES index components
- SES method
- Blended SES index (ACS + FRL)
- SES index value
- 98.6
- FRL %
- 6.6%
- ELL %
- 8.3% · WA OSPI Report Card Enrollment
- SPED %
- 10.4% · WA OSPI Report Card Enrollment
- Tract median income (ACS 5-year)
- $250,001
- Tract poverty rate
- 1.6%
- Tract % bachelor's+
- 86.0%
What "Decoded Rank" means
Decoded Rank converts School Alpha — the context-adjusted residual — into a parent-facing rank within the metro pool. A higher Decoded Rank than Achievement Rank means the school's raw scores understate its performance once neighborhood and school context are held constant. The reverse means raw scores overstate it. The rank is one signal, not a verdict.