West Marin Elementary: math

The shaded band is this school's normal range. If nothing about how it works changes, nearly every future year should land inside it. Zero means the typical student just meets the state standard. The small numbers under the years are how many students were tested.

Step 1 · Each year's result

For each grade tested, take the average (mean) scale score from the California Department of Education's results file, and subtract the lowest score that counts as "Standard Met" for that grade. That is the grade's distance from standard. Weight each grade by its share of the students tested, then add the grades up. Grades where the state hides the average because ten or fewer students tested are left out entirely.

2015 from sb_ca2015_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	42,753	2482.4	− 2436	46.4	× 14 / 100	6.5
4	42,756	2437.0	− 2485	−48	× 26 / 100	−12.5
5	42,757	2492.1	− 2528	−35.9	× 17 / 100	−6.1
6	42,760	2569.2	− 2552	17.2	× 13 / 100	2.2
7	42,761	2544.8	− 2567	−22.2	× 18 / 100	−4
8	42,764	2545.7	− 2586	−40.3	× 12 / 100	−4.8
Sum, rounded to a whole point						−19

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	39,485	2453.6	− 2436	17.6	× 15 / 102	2.6
4	39,488	2525.7	− 2485	40.7	× 13 / 102	5.2
5	39,489	2468.7	− 2528	−59.3	× 25 / 102	−14.5
6	39,491	2480.3	− 2552	−71.7	× 17 / 102	−12
7	39,493	2602.0	− 2567	35	× 15 / 102	5.1
8	39,496	2551.5	− 2586	−34.5	× 17 / 102	−5.8
Sum, rounded to a whole point						−19

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,508	2415.9	− 2436	−20.1	× 24 / 112	−4.3
4	40,511	2497.5	− 2485	12.5	× 13 / 112	1.5
5	40,513	2544.6	− 2528	16.6	× 14 / 112	2.1
6	40,515	2460.8	− 2552	−91.2	× 26 / 112	−21.2
7	40,516	2545.9	− 2567	−21.1	× 21 / 112	−4
8	40,519	2598.9	− 2586	12.9	× 14 / 112	1.6
Sum, rounded to a whole point						−24

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,505	2409.8	− 2436	−26.2	× 20 / 123	−4.3
4	40,508	2440.0	− 2485	−45	× 22 / 123	−8
5	40,509	2505.5	− 2528	−22.5	× 13 / 123	−2.4
6	40,512	2536.2	− 2552	−15.8	× 19 / 123	−2.4
7	40,513	2500.3	− 2567	−66.7	× 28 / 123	−15.2
8	40,516	2525.6	− 2586	−60.4	× 21 / 123	−10.3
Sum, rounded to a whole point						−43

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,650	2412.0	− 2436	−24	× 20 / 122	−3.9
4	40,651	2459.7	− 2485	−25.3	× 19 / 122	−3.9
5	40,652	2468.0	− 2528	−60	× 26 / 122	−12.8
6	40,653	2483.9	− 2552	−68.1	× 14 / 122	−7.8
7	40,654	2567.0	− 2567	0	× 18 / 122	0
8	40,655	2513.3	− 2586	−72.7	× 25 / 122	−14.9
Sum, rounded to a whole point						−43

2021 from sb_ca2021_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	39,587	2373.9	− 2436	−62.1	× 14 / 81	−10.7
4	39,588	2408.6	− 2485	−76.4	× 13 / 81	−12.3
5	39,589	2483.7	− 2528	−44.3	× 19 / 81	−10.4
6	39,590	2487.8	− 2552	−64.2	× 12 / 81	−9.5
7	39,591	2514.2	− 2567	−52.8	× 23 / 81	−15
Sum, rounded to a whole point						−58

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,411	2404.3	− 2436	−31.7	× 15 / 106	−4.5
4	40,412	2450.3	− 2485	−34.7	× 17 / 106	−5.6
5	40,413	2468.7	− 2528	−59.3	× 17 / 106	−9.5
6	40,414	2517.4	− 2552	−34.6	× 20 / 106	−6.5
7	40,415	2480.5	− 2567	−86.5	× 15 / 106	−12.2
8	40,416	2530.3	− 2586	−55.7	× 22 / 106	−11.6
Sum, rounded to a whole point						−50

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,458	2392.4	− 2436	−43.6	× 13 / 100	−5.7
4	40,459	2456.1	− 2485	−28.9	× 16 / 100	−4.6
5	40,460	2437.6	− 2528	−90.4	× 16 / 100	−14.5
6	40,461	2435.0	− 2552	−117	× 16 / 100	−18.7
7	40,462	2521.0	− 2567	−46	× 21 / 100	−9.7
8	40,463	2466.9	− 2586	−119.1	× 18 / 100	−21.4
Sum, rounded to a whole point						−75

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,279	2426.0	− 2436	−10	× 16 / 94	−1.7
4	40,280	2427.3	− 2485	−57.7	× 13 / 94	−8
5	40,281	2455.1	− 2528	−72.9	× 15 / 94	−11.6
6	40,282	2509.4	− 2552	−42.6	× 19 / 94	−8.6
7	40,283	2417.8	− 2567	−149.2	× 13 / 94	−20.6
8	40,284	2532.4	− 2586	−53.6	× 18 / 94	−10.3
Sum, rounded to a whole point						−61

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	40,060	2430.2	− 2436	−5.8	× 13 / 75	−1
4	40,061	2462.4	− 2485	−22.6	× 15 / 75	−4.5
6	40,063	2566.8	− 2552	14.8	× 15 / 75	3
7	40,064	2481.5	− 2567	−85.5	× 20 / 75	−22.8
8	40,065	2496.7	− 2586	−89.3	× 12 / 75	−14.3
Sum, rounded to a whole point						−40

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −19, −19, −24, −43, −43, −58, −50, −75, −61, −40 → −43.2
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2015→2016: 0 · 2016→2017: 5 · 2017→2018: 19 · 2018→2019: 0 · 2019→2021: 15 · 2021→2022: 8 · 2022→2023: 25 · 2023→2024: 14 · 2024→2025: 21 → average 11.9
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 11.9 × 2.66 = 31.7. Upper limit −11.5, lower limit −74.9.

Why 2.66? It is the standard factor from quality control, the work of Walter Shewhart and W. Edwards Deming. It turns "how much the result typically changes in a year" into "how far it can wander by chance alone".

Years with no result (no state tests were given in spring 2020) are skipped: the year-to-year change runs from the last year with a result to the next one.

Step 3 · Free or reduced-price meals

The share of enrolled students eligible for free or reduced-price meals. From 2014–15, 2015–16, 2016–17, 2017–18, 2018–19, 2020–21, 2021–22, 2022–23, 2023–24, 2024–25, 2025–26.