Independent Study, Sojourner Truth: 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
11	3,110	2486.9	− 2628	−141.1	× 9 / 9	−141.1
Sum, rounded to a whole point						−141

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	2,821	2461.0	− 2628	−167	× 49 / 49	−167
Sum, rounded to a whole point						−167

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	2,894	2488.5	− 2628	−139.5	× 24 / 24	−139.5
Sum, rounded to a whole point						−140

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	2,918	2448.7	− 2628	−179.3	× 26 / 26	−179.3
Sum, rounded to a whole point						−179

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	2,816	2341.2	− 2436	−94.8	× 52 / 253	−19.5
4	2,817	2397.8	− 2485	−87.2	× 12 / 253	−4.1
5	2,818	2398.5	− 2528	−129.5	× 36 / 253	−18.4
6	2,819	2440.0	− 2552	−112	× 44 / 253	−19.5
7	2,820	2465.1	− 2567	−101.9	× 43 / 253	−17.3
8	2,821	2450.4	− 2586	−135.6	× 39 / 253	−20.9
11	2,822	2503.2	− 2628	−124.8	× 27 / 253	−13.3
Sum, rounded to a whole point						−113

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	2,750	2375.2	− 2436	−60.8	× 24 / 155	−9.4
5	2,752	2463.8	− 2528	−64.2	× 12 / 155	−5
6	2,753	2397.5	− 2552	−154.5	× 17 / 155	−16.9
7	2,754	2481.4	− 2567	−85.6	× 36 / 155	−19.9
8	2,755	2467.3	− 2586	−118.7	× 32 / 155	−24.5
11	2,756	2547.7	− 2628	−80.3	× 34 / 155	−17.6
Sum, rounded to a whole point						−93

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	2,714	2350.9	− 2436	−85.1	× 22 / 150	−12.5
4	2,715	2373.2	− 2485	−111.8	× 24 / 150	−17.9
5	2,716	2379.8	− 2528	−148.2	× 15 / 150	−14.8
6	2,717	2463.0	− 2552	−89	× 18 / 150	−10.7
7	2,718	2475.7	− 2567	−91.3	× 23 / 150	−14
8	2,719	2483.0	− 2586	−103	× 33 / 150	−22.7
11	2,720	2534.0	− 2628	−94	× 15 / 150	−9.4
Sum, rounded to a whole point						−102

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	2,690	2311.5	− 2436	−124.5	× 22 / 166	−16.5
4	2,691	2396.7	− 2485	−88.3	× 16 / 166	−8.5
5	2,692	2398.5	− 2528	−129.5	× 21 / 166	−16.4
6	2,693	2468.2	− 2552	−83.8	× 24 / 166	−12.1
7	2,694	2514.8	− 2567	−52.2	× 21 / 166	−6.6
8	2,695	2508.3	− 2586	−77.7	× 35 / 166	−16.4
11	2,696	2665.0	− 2628	37	× 27 / 166	6
Sum, rounded to a whole point						−70

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −141, −167, −140, −179, −113, −93, −102, −70 → −125.6
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2015→2016: 26 · 2016→2017: 27 · 2017→2019: 39 · 2019→2022: 66 · 2022→2023: 20 · 2023→2024: 9 · 2024→2025: 32 → average 31.3
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 31.3 × 2.66 = 83.3. Upper limit −42.3, lower limit −208.9.

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.