Some Well-Known Forces That Shape Supply and Demand
A report from the Southern Regional Education Board, September 1998
The purpose of this introduction is to provide the reader with a brief overview of the components and factors that shape supply and demand. Given this overview, the interpretation of the numerous facts presented in the report can be placed into this general structure of supply and demand presented below.
Analyzing the supply and demand for educators requires understanding the forces that shape the inflow and outflow of educators from public primary and secondary education, and the demographic factors which sustain and alter the number of students among districts.
Supply is composed of educators who are retained as educators from one year to the next, educators returning to education after some period of absence, and new entrants without any previous teaching experience.
Retained educators can be considered in terms of those that remain in their same position from one year to the next, or change positions. Further, such educators may change districts from one year to the next. Retention is the primary source of supply of educators, accounting from more than 90% of the supply for most positions. Thus, understanding the factors that influence attrition is important. The most important factor that conditions the rate of attrition is the number of years of experience. New teachers exit at very high rates for the first 10 years. Then educators remain at rates often exceeding 96% retention, until the 20th year of experience arrives. Then the rate of attrition climbs again as educators start to retire. So having a steady supply of new teachers is essential, and observing how the existing workforce ages is just as important.
New entrants, who have bachelor degrees, from institutions of higher education enter at public primary and secondary education at the greatest rates just after graduation. The rate of entry (or the yield) then drops off dramatically. This kind of yield is true of exiting teachers as well---the greatest number returns within 1 year of absence, then the number that return drops greatly.
Enrollments of students by grades follow quite predictable patterns or movement from one grade to the next. Kindergarten students are the most difficult to predict, as we must rely on live births counts five years previous to make the estimate. Economic conditions that change in or out migration, or alter the preference for private school attendance can have a substantial influence on enrollments. Enrollments, in conjunction with course taking behavior on the part of students in middle and high school, and mandated – or recommended--student to teacher ratios drive the level of demand.
The matter of supply and demand increases in complexity when considering how it varies by grade, subject area, district, gender, and ethnicity. Indeed, some districts have many applicants while other have few. Some subject areas have a glut of trained and certified individuals, others have a shortage. Some positions are largely male, others female. Some positions are well-represented by a diversity of ethnic groups, others are not.
This report provides information about many of these forces, and uses the trends in the data to present a supply and demand projection to the year 2002.
