Projection Methodology and Reliability
PROJECTION METHODOLOGY
Cohort component (survival) technique is a frequently used method of preparing enrollment forecasts. NESDEC uses this method, but modifies it in order to move away from forecasts that are wholly computer- or formula-driven. Such modification permits the incorporation of important, current district-specific demographic information into the generation of enrollment forecasts (such as in/out-migration of students, resident births, HUD-reported building permits, etc.). Percentages are calculated from the historical enrollment data to determine a reliable percentage of increase or decrease in enrollment between any two grades. For example, if 100 students enrolled in Grade 1 in 2023-24 increased to 104 students in Grade 2 in 2024-25, the percentage of survival would be 104%, or a ratio of 1.04. Ratios are calculated between each pair of grades or years in school over several recent years. After study and analysis of the historical ratios, and based upon a reasonable set of assumptions regarding births, migration rates, retention rates, etc., ratios most indicative of future growth patterns are determined for each pair of grades. The ratios thus selected are applied to the present enrollment statistics to project into future years. The ratios are the key factors in the reliability of the projections, assuming validity of the data at the starting point.
RELIABILITY OF ENROLLMENT PROJECTIONS
Projections can serve as useful guides to school administrators for educational planning. Enrollment projections are more reliable in Years #1-3 in the future and less reliable in the “out-years.” Projections four to ten years out may serve as a guide to future enrollments and are useful for planning purposes, but they should be viewed as subject to change given the likelihood of potential shifts in underlying assumptions/trends, such as student migration, births as they relate to Kindergarten enrollment, and other factors. Projections that are based upon the children who already are in the district (the current K-12 population only) will be the most reliable. The second level of reliability will be for those children already born into the community but not yet old enough to be in school. The least reliable category is the group for which an estimate must be made to predict the number of births , thereby adding additional uncertainty. See these three multi-colored groupings on the “Projected Enrollment" tab. Annual updates allow for early identification of recent changes in historical trends. When the actual enrollment in a grade is significantly different (higher or lower) from the projected number, it is important (yet difficult) to determine whether this is a one-year aberration or whether a new trend may have begun. In light of this possibility, NESDEC urges all school districts to have updated enrollment forecasts developed by NESDEC each October. This service is available at no cost to affiliated school districts.
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