Contra Costa School Of Performing Arts: 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.

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,386	2469.2	− 2552	−82.8	× 84 / 193	−36
7	5,388	2507.5	− 2567	−59.5	× 59 / 193	−18.2
8	5,391	2502.3	− 2586	−83.7	× 50 / 193	−21.7
Sum, rounded to a whole point						−76

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,381	2503.7	− 2552	−48.3	× 91 / 256	−17.2
7	5,382	2499.2	− 2567	−67.8	× 81 / 256	−21.5
8	5,385	2540.9	− 2586	−45.1	× 67 / 256	−11.8
11	5,386	2592.1	− 2628	−35.9	× 17 / 256	−2.4
Sum, rounded to a whole point						−53

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,433	2491.4	− 2552	−60.6	× 94 / 310	−18.4
7	5,434	2520.5	− 2567	−46.5	× 94 / 310	−14.1
8	5,435	2509.8	− 2586	−76.2	× 87 / 310	−21.4
11	5,436	2580.1	− 2628	−47.9	× 35 / 310	−5.4
Sum, rounded to a whole point						−59

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,268	2449.5	− 2552	−102.5	× 73 / 266	−28.1
7	5,269	2493.7	− 2567	−73.3	× 83 / 266	−22.9
8	5,270	2480.3	− 2586	−105.7	× 86 / 266	−34.2
11	5,271	2510.7	− 2628	−117.3	× 24 / 266	−10.6
Sum, rounded to a whole point						−96

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,264	2413.0	− 2552	−139	× 38 / 216	−24.5
7	5,265	2479.1	− 2567	−87.9	× 82 / 216	−33.4
8	5,266	2494.9	− 2586	−91.1	× 60 / 216	−25.3
11	5,267	2502.5	− 2628	−125.5	× 36 / 216	−20.9
Sum, rounded to a whole point						−104

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,203	2423.4	− 2552	−128.6	× 62 / 223	−35.8
7	5,204	2465.5	− 2567	−101.5	× 52 / 223	−23.7
8	5,205	2490.6	− 2586	−95.4	× 86 / 223	−36.8
11	5,206	2539.4	− 2628	−88.6	× 23 / 223	−9.1
Sum, rounded to a whole point						−105

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
6	5,165	2472.3	− 2552	−79.7	× 29 / 142	−16.3
7	5,166	2491.9	− 2567	−75.1	× 50 / 142	−26.4
8	5,167	2479.0	− 2586	−107	× 43 / 142	−32.4
11	5,168	2513.8	− 2628	−114.2	× 20 / 142	−16.1
Sum, rounded to a whole point						−91

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −76, −53, −59, −96, −104, −105, −91 → −83.4
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2017→2018: 23 · 2018→2019: 6 · 2019→2022: 37 · 2022→2023: 8 · 2023→2024: 1 · 2024→2025: 14 → average 14.8
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 14.8 × 2.66 = 39.4. Upper limit −44, lower limit −122.8.

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 2016–17, 2017–18, 2018–19, 2020–21, 2021–22, 2022–23, 2023–24, 2024–25.