Napa County Office Of Education: math

The shaded band is this district'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	46,714	2401.1	− 2628	−226.9	× 13 / 13	−226.9
Sum, rounded to a whole point						−227

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
7	43,429	2351.6	− 2567	−215.4	× 11 / 53	−44.7
8	43,432	2413.0	− 2586	−173	× 14 / 53	−45.7
11	43,433	2424.7	− 2628	−203.3	× 28 / 53	−107.4
Sum, rounded to a whole point						−198

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
8	44,497	2369.6	− 2586	−216.4	× 16 / 54	−64.1
11	44,499	2426.7	− 2628	−201.3	× 38 / 54	−141.7
Sum, rounded to a whole point						−206

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
8	44,509	2370.9	− 2586	−215.1	× 13 / 39	−71.7
11	44,511	2386.5	− 2628	−241.5	× 26 / 39	−161
Sum, rounded to a whole point						−233

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
8	44,649	2391.8	− 2586	−194.2	× 16 / 44	−70.6
11	44,650	2403.0	− 2628	−225	× 28 / 44	−143.2
Sum, rounded to a whole point						−214

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	44,400	2401.8	− 2628	−226.2	× 20 / 20	−226.2
Sum, rounded to a whole point						−226

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	44,384	2377.4	− 2628	−250.6	× 34 / 34	−250.6
Sum, rounded to a whole point						−251

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	44,220	2386.3	− 2628	−241.7	× 24 / 24	−241.7
Sum, rounded to a whole point						−242

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
11	43,951	2399.5	− 2628	−228.5	× 18 / 18	−228.5
Sum, rounded to a whole point						−229

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −227, −198, −206, −233, −214, −226, −251, −242, −229 → −225.1
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2015→2016: 29 · 2016→2017: 8 · 2017→2018: 27 · 2018→2019: 19 · 2019→2022: 12 · 2022→2023: 25 · 2023→2024: 9 · 2024→2025: 13 → average 17.8
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 17.8 × 2.66 = 47.3. Upper limit −177.8, lower limit −272.4.

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 district, 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.