The Government Accountability Office has a report titled "Varied State Criteria May Contribute to Differences in Percentages of Children Served."
Differences in states’ eligibility criteria and the difficulty of identifying and evaluating some children suspected of having disabilities may contribute to differences in the percentages of children receiving special education services across states. The Individuals with Disabilities Education Act (IDEA), the primary federal special education law, requires states to have policies and procedures in place to ensure that all children with disabilities residing in the state who need special education services are identified, located, and evaluated. These policies and procedures—known as “Child Find”—are generally implemented by local school districts (see fig.). IDEA gives states some latitude in setting eligibility criteria and defining disability categories. In addition, states may determine their own processes for identifying and evaluating children. As a result, a child eligible for services in one state might be ineligible in another. According to advocates, special education subject matter specialists, and state and local officials GAO interviewed, a number of challenges related to correctly identifying and evaluating children suspected of having a disability can affect eligibility decisions. For example, school district officials in all four states GAO visited cited challenges in properly identifying and evaluating English Learner students, as districts do not always have staff who are conversant in a child’s first language and skilled in distinguishing language proficiency from disabilities
READ GAO REPORT: "Special Education: Varied (US) State Criteria May Contribute to Differences in %'s of Children Served" HERE: https://t.co/IUXrgcg7hw Betsy DeVos & her #ALECideas = Privatize schools, make $, but leave the special needs kids in public schools. #TBATs #SpecialEd pic.twitter.com/bko2pw8Q9B— Hector Solon (@HectorSolon) April 25, 2019