Método de Pesquisa

The NLTS2 is a nationally representative sample of over eleven thousand 13- to 17-year-old stu dents who were receiving special education ser vices during the 2000–2001 school year. NLTS2 participants were followed over a 10-year period resulting in five waves of data collection (one wave every 2 years with Waves 1–3 available for the current study). The NLTS2 is based on a two-stage stratified, clustered sample design. A stratified random sample of local education agen cies (LEAs) was first selected from the universe of LEAs that provided special education services to students in Grades 7 through 12. LEAs were stratified on the basis of region, enrollment size, and community wealth. Out of the stratified sample of 3,646 LEAs and 77 special schools, 501 LEAs and 38 special schools agreed to par ticipate. The roster of students receiving special education services from each of the participating LEAs and special schools was then stratified by disability category. Students were randomly se lected from each disability category, but with re spect to a sampling fraction that would permit an acceptable level of precision in associated param eter estimates (i.e., standard errors < 3.6%). The sampling design allows for generalizations to ado lescents in the following 12 disability categories: autism, traumatic brain injury, deaf-blindness, LD, mental retardation (MR), emotional distur bance (ED), multiple disabilities, and hearing, speech, visual, orthopedic, and other health im pairments (SRI International, 2000). It should be noted that mental retardation is the terminology used within the NLTS2 and by school districts; however, within the current article we will use the more recent term adopted for this population of intellectual disability.