Contra Costa: math

The shaded band is this county'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	5,735	2430.6	− 2436	−5.4	× 13380 / 89740	−0.8
4	5,738	2472.3	− 2485	−12.7	× 12914 / 89740	−1.8
5	5,739	2499.0	− 2528	−29	× 13310 / 89740	−4.3
6	5,742	2527.3	− 2552	−24.7	× 13176 / 89740	−3.6
7	5,743	2538.6	− 2567	−28.4	× 13010 / 89740	−4.1
8	5,746	2550.7	− 2586	−35.3	× 12808 / 89740	−5
11	5,747	2576.1	− 2628	−51.9	× 11142 / 89740	−6.4
Sum, rounded to a whole point						−26

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,201	2436.3	− 2436	0.3	× 12931 / 91286	0
4	5,202	2475.3	− 2485	−9.7	× 13531 / 91286	−1.4
5	5,204	2503.1	− 2528	−24.9	× 13087 / 91286	−3.6
6	5,206	2528.1	− 2552	−23.9	× 13341 / 91286	−3.5
7	5,208	2545.9	− 2567	−21.1	× 13142 / 91286	−3
8	5,210	2560.2	− 2586	−25.8	× 13041 / 91286	−3.7
11	5,213	2589.6	− 2628	−38.4	× 12213 / 91286	−5.1
Sum, rounded to a whole point						−20

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,306	2437.1	− 2436	1.1	× 12663 / 92151	0.2
4	5,309	2474.7	− 2485	−10.3	× 13077 / 92151	−1.5
5	5,311	2499.0	− 2528	−29	× 13653 / 92151	−4.3
6	5,312	2525.6	− 2552	−26.4	× 13131 / 92151	−3.8
7	5,315	2541.7	− 2567	−25.3	× 13424 / 92151	−3.7
8	5,316	2561.3	− 2586	−24.7	× 13243 / 92151	−3.5
11	5,319	2583.6	− 2628	−44.4	× 12960 / 92151	−6.2
Sum, rounded to a whole point						−23

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,311	2437.5	− 2436	1.5	× 12463 / 91610	0.2
4	5,312	2475.6	− 2485	−9.4	× 12798 / 91610	−1.3
5	5,315	2500.5	− 2528	−27.5	× 13095 / 91610	−3.9
6	5,316	2523.1	− 2552	−28.9	× 13635 / 91610	−4.3
7	5,319	2540.2	− 2567	−26.8	× 13162 / 91610	−3.9
8	5,320	2556.3	− 2586	−29.7	× 13505 / 91610	−4.4
11	5,323	2582.0	− 2628	−46	× 12952 / 91610	−6.5
Sum, rounded to a whole point						−24

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,358	2440.2	− 2436	4.2	× 12592 / 91188	0.6
4	5,359	2477.0	− 2485	−8	× 12563 / 91188	−1.1
5	5,360	2502.6	− 2528	−25.4	× 12944 / 91188	−3.6
6	5,361	2520.8	− 2552	−31.2	× 13117 / 91188	−4.5
7	5,362	2537.8	− 2567	−29.2	× 13703 / 91188	−4.4
8	5,363	2553.3	− 2586	−32.7	× 13161 / 91188	−4.7
11	5,364	2586.5	− 2628	−41.5	× 13108 / 91188	−6
Sum, rounded to a whole point						−24

2021 from sb_ca2021_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,120	2432.4	− 2436	−3.6	× 2333 / 17698	−0.5
4	5,121	2457.7	− 2485	−27.3	× 2584 / 17698	−4
5	5,122	2482.1	− 2528	−45.9	× 2580 / 17698	−6.7
6	5,123	2508.0	− 2552	−44	× 2257 / 17698	−5.6
7	5,124	2531.6	− 2567	−35.4	× 2251 / 17698	−4.5
8	5,125	2550.7	− 2586	−35.3	× 2280 / 17698	−4.5
11	5,126	2621.0	− 2628	−7	× 3413 / 17698	−1.3
Sum, rounded to a whole point						−27

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,195	2428.7	− 2436	−7.3	× 11743 / 84307	−1
4	5,196	2467.0	− 2485	−18	× 12145 / 84307	−2.6
5	5,197	2488.1	− 2528	−39.9	× 12307 / 84307	−5.8
6	5,198	2507.4	− 2552	−44.6	× 12117 / 84307	−6.4
7	5,199	2519.5	− 2567	−47.5	× 11921 / 84307	−6.7
8	5,200	2530.6	− 2586	−55.4	× 12189 / 84307	−8
11	5,201	2569.5	− 2628	−58.5	× 11885 / 84307	−8.2
Sum, rounded to a whole point						−39

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,197	2431.1	− 2436	−4.9	× 12148 / 85883	−0.7
4	5,198	2470.2	− 2485	−14.8	× 12005 / 85883	−2.1
5	5,199	2493.5	− 2528	−34.5	× 12277 / 85883	−4.9
6	5,200	2505.0	− 2552	−47	× 12286 / 85883	−6.7
7	5,201	2523.4	− 2567	−43.6	× 12218 / 85883	−6.2
8	5,202	2528.7	− 2586	−57.3	× 12123 / 85883	−8.1
11	5,203	2562.6	− 2628	−65.4	× 12826 / 85883	−9.8
Sum, rounded to a whole point						−38

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,132	2429.2	− 2436	−6.8	× 11798 / 85719	−0.9
4	5,133	2470.7	− 2485	−14.3	× 12310 / 85719	−2.1
5	5,134	2492.3	− 2528	−35.7	× 12141 / 85719	−5.1
6	5,135	2510.0	− 2552	−42	× 12302 / 85719	−6
7	5,136	2523.7	− 2567	−43.3	× 12299 / 85719	−6.2
8	5,137	2537.3	− 2586	−48.7	× 12301 / 85719	−7
11	5,138	2565.9	− 2628	−62.1	× 12568 / 85719	−9.1
Sum, rounded to a whole point						−36

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,096	2429.8	− 2436	−6.2	× 12002 / 85688	−0.9
4	5,097	2471.4	− 2485	−13.6	× 11923 / 85688	−1.9
5	5,098	2497.4	− 2528	−30.6	× 12465 / 85688	−4.5
6	5,099	2514.1	− 2552	−37.9	× 12091 / 85688	−5.3
7	5,100	2532.1	− 2567	−34.9	× 12372 / 85688	−5
8	5,101	2543.7	− 2586	−42.3	× 12361 / 85688	−6.1
11	5,102	2574.4	− 2628	−53.6	× 12474 / 85688	−7.8
Sum, rounded to a whole point						−32

2026 from sb_ca2026_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	5,098	2435.0	− 2436	−1	× 11295 / 84141	−0.1
4	5,099	2474.0	− 2485	−11	× 12011 / 84141	−1.6
5	5,100	2495.2	− 2528	−32.8	× 11959 / 84141	−4.7
6	5,101	2515.5	− 2552	−36.5	× 12337 / 84141	−5.4
7	5,102	2533.3	− 2567	−33.7	× 12048 / 84141	−4.8
8	5,103	2552.1	− 2586	−33.9	× 12276 / 84141	−4.9
11	5,104	2579.4	− 2628	−48.6	× 12215 / 84141	−7.1
Sum, rounded to a whole point						−29

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −26, −20, −23, −24, −24, −27, −39, −38, −36, −32, −29 → −28.9
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2015→2016: 6 · 2016→2017: 3 · 2017→2018: 1 · 2018→2019: 0 · 2019→2021: 3 · 2021→2022: 12 · 2022→2023: 1 · 2023→2024: 2 · 2024→2025: 4 · 2025→2026: 3 → average 3.5
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 3.5 × 2.66 = 9.3. Upper limit −19.6, lower limit −38.2.

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 — for a county, the total across its schools. From 2014–15, 2015–16, 2016–17, 2017–18, 2018–19, 2020–21, 2021–22, 2022–23, 2023–24, 2024–25, 2025–26.