TABLE 1

Categorization of Wisconsin Elementary Schools Into Octiles According to 2002 Autism Special Education Category Prevalence

GroupNo. of Students in 2002–2003Proportion of Wisconsin Elementary School Students, %No. of School Districts2002 Autism Category Prevalence, Mean (Range), Cases per 1000 Students
Highest octile in 200251 19012.66111.2 (8.2–29.3)
2nd octile51 18412.6427.1 (6.3–8.2)
3rd octile48 92812.0435.6 (5.1–6.2)
4th octile42 51810.4314.8 (4.3–6.1)
5th octile (Milwaukee metropolitan area)56 52413.914.2
6th octile59 43514.6523.7 (3.1–4.2)
7th octile47 59211.7662.4 (1.7–3.1)
Lowest octile50 40412.41160.5 (0–1.7)
Wisconsin elementary school total407 775100.04124.9 (0–29.3)