The method used to project special education personnel is taken from work completed by Jim Wilson (1991). This methodology was selected because it is a simple model that required data on few new variables to be collected by States, yet is expected to yield accurate projections at the State level. The projection model adopted by OSEP to project personnel demand is:
The purpose of the model is to enable States and OSEP to predict the number of new teachers that will be needed to be hired to fill vacant positions and those not fully certified. These new hires may come from the new university graduates, from the pool of teachers who have temporarily left the school systems, or from regular education teachers who become certified for special education. The model uses three basic data elements to project the number of these individuals: student enrollment, retained personnel, and student/personnel ratio.
Five-year projections of the number of students enrolled, the student/teacher ratio, and the number of teachers retained each year have been entered into the model. These projections are based on historical data for each of these elements. The 1993-94 school year was the first year that data were collected on the number of personnel retained from the previous year. This category represents a subset of the total number of personnel employed. In 1993-94, States reported that 270,027 (87 percent) of the employed, fully certified teachers were retained from the previous year. Additionally, States reported that 13,169 (62.5 percent) of the teachers not fully certified were retained from the previous year.
States found it difficult to provide the number of retained teachers during this first year of data collection. The majority of States initially reported, for at least one category of personnel, greater numbers of retained than employed personnel. Corrected data were later provided by those States. Projections using the number of personnel retained will have to be delayed until a second year of data have been received.