New Zealand Statistical Association
2004 Conference

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Laurie Fleming (and Lera Kazakova)
Sysware Consulting Group Ltd (and Ministry of Education)

Short-term School Roll Projection Model

Lera Kazakova, Ministry of Education
Laurie Fleming, DataMax Consulting Ltd

Recently the Ministry of Education shifted from using a population-based school roll projection model to a trend-estimation based model for producing a short-term 5-year projection. Such projections are necessary for identifying the Property Business Cases that occur when additional classrooms are required in schools.

In the new model a trend for each individual school is obtained by applying a 5- or 3-term Henderson filter. Then the estimated trend is forecast using a standard technique. This model is almost completely based on the school roll history and hence is responsive to changes in popularity or enrolment schemes, contrary to the previous model which was responsive to the local area population changes only. The new school roll projection model proved to be more accurate when tested on historical data and this year's business case round.

A relative contribution of volatility to growth estimator was employed to evaluate the volatility of school roll data and explain the achieved accuracy in projection. To increase the overall accuracy in the identified property business cases, some additional techniques have been developed for decreasing the number of false positives and false negatives.