Chico Country Day: 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	4,619	2463.4	− 2436	27.4	× 61 / 355	4.7
4	4,620	2499.0	− 2485	14	× 60 / 355	2.4
5	4,623	2495.1	− 2528	−32.9	× 61 / 355	−5.7
6	4,624	2523.9	− 2552	−28.1	× 59 / 355	−4.7
7	4,627	2538.1	− 2567	−28.9	× 61 / 355	−5
8	4,628	2597.8	− 2586	11.8	× 53 / 355	1.8
Sum, rounded to a whole point						−6

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,125	2468.9	− 2436	32.9	× 60 / 359	5.5
4	4,126	2501.9	− 2485	16.9	× 60 / 359	2.8
5	4,129	2527.2	− 2528	−0.8	× 61 / 359	−0.1
6	4,130	2522.5	− 2552	−29.5	× 62 / 359	−5.1
7	4,132	2556.2	− 2567	−10.8	× 60 / 359	−1.8
8	4,134	2578.7	− 2586	−7.3	× 56 / 359	−1.1
Sum, rounded to a whole point						0

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,198	2479.3	− 2436	43.3	× 62 / 365	7.4
4	4,201	2492.5	− 2485	7.5	× 58 / 365	1.2
5	4,202	2538.5	− 2528	10.5	× 61 / 365	1.8
6	4,204	2566.9	− 2552	14.9	× 61 / 365	2.5
7	4,207	2539.9	− 2567	−27.1	× 62 / 365	−4.6
8	4,209	2568.3	− 2586	−17.7	× 61 / 365	−3
Sum, rounded to a whole point						5

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,201	2465.6	− 2436	29.6	× 60 / 367	4.8
4	4,202	2512.6	− 2485	27.6	× 62 / 367	4.7
5	4,205	2516.3	− 2528	−11.7	× 61 / 367	−1.9
6	4,206	2556.3	− 2552	4.3	× 64 / 367	0.7
7	4,209	2588.6	− 2567	21.6	× 59 / 367	3.5
8	4,210	2579.2	− 2586	−6.8	× 61 / 367	−1.1
Sum, rounded to a whole point						11

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,257	2461.6	− 2436	25.6	× 62 / 367	4.3
4	4,258	2511.8	− 2485	26.8	× 61 / 367	4.5
5	4,259	2549.0	− 2528	21	× 62 / 367	3.5
6	4,260	2537.0	− 2552	−15	× 62 / 367	−2.5
7	4,261	2594.7	− 2567	27.7	× 64 / 367	4.8
8	4,262	2594.7	− 2586	8.7	× 56 / 367	1.3
Sum, rounded to a whole point						16

2021 from sb_ca2021_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,101	2446.0	− 2436	10	× 61 / 349	1.7
4	4,102	2449.3	− 2485	−35.7	× 57 / 349	−5.8
5	4,103	2495.2	− 2528	−32.8	× 61 / 349	−5.7
6	4,104	2541.3	− 2552	−10.7	× 61 / 349	−1.9
7	4,105	2584.5	− 2567	17.5	× 55 / 349	2.8
8	4,106	2576.1	− 2586	−9.9	× 54 / 349	−1.5
Sum, rounded to a whole point						−10

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,175	2424.8	− 2436	−11.2	× 61 / 355	−1.9
4	4,176	2474.7	− 2485	−10.3	× 62 / 355	−1.8
5	4,177	2499.6	− 2528	−28.4	× 62 / 355	−5
6	4,178	2498.5	− 2552	−53.5	× 58 / 355	−8.7
7	4,179	2578.3	− 2567	11.3	× 57 / 355	1.8
8	4,180	2601.7	− 2586	15.7	× 55 / 355	2.4
Sum, rounded to a whole point						−13

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,156	2446.5	− 2436	10.5	× 61 / 356	1.8
4	4,157	2477.9	− 2485	−7.1	× 61 / 356	−1.2
5	4,158	2485.6	− 2528	−42.4	× 61 / 356	−7.3
6	4,159	2512.1	− 2552	−39.9	× 57 / 356	−6.4
7	4,160	2517.5	− 2567	−49.5	× 60 / 356	−8.3
8	4,161	2555.7	− 2586	−30.3	× 56 / 356	−4.8
Sum, rounded to a whole point						−26

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,121	2441.5	− 2436	5.5	× 60 / 359	0.9
4	4,122	2491.8	− 2485	6.8	× 62 / 359	1.2
5	4,123	2508.8	− 2528	−19.2	× 59 / 359	−3.2
6	4,124	2533.4	− 2552	−18.6	× 56 / 359	−2.9
7	4,125	2555.1	− 2567	−11.9	× 61 / 359	−2
8	4,126	2545.1	− 2586	−40.9	× 61 / 359	−6.9
Sum, rounded to a whole point						−13

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	4,075	2453.3	− 2436	17.3	× 63 / 356	3.1
4	4,076	2478.9	− 2485	−6.1	× 61 / 356	−1
5	4,077	2523.4	− 2528	−4.6	× 62 / 356	−0.8
6	4,078	2538.5	− 2552	−13.5	× 57 / 356	−2.2
7	4,079	2558.2	− 2567	−8.8	× 53 / 356	−1.3
8	4,080	2570.1	− 2586	−15.9	× 60 / 356	−2.7
Sum, rounded to a whole point						−5

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −6, 0, 5, 11, 16, −10, −13, −26, −13, −5 → −4.1
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: 5 · 2017→2018: 6 · 2018→2019: 5 · 2019→2021: 26 · 2021→2022: 3 · 2022→2023: 13 · 2023→2024: 13 · 2024→2025: 8 → average 9.4
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 9.4 × 2.66 = 25. Upper limit 20.9, lower limit −29.1.

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.