Cohort analysis technique for long-term manpower planning : The case of a Hong Kong tertiary institution

This paper considers the problem of long-term manpower planning on the number of teaching staff for the case of a tertiary institution - the City Polytechnic of Hong Kong (CPHK). Due to the high turnover experienced in recent years, it is found necessary to study the wastage pattern of staff, defined as the number of new appointees who have left CPHK employment, rather than simply addressing just the issue of strength (namely number in post). A cohort analysis technique is therefore applied to characterize statistically the wastage rate as related to the length of service of individual cohorts of staff, being groups of newcomers joining CPHK in the same periods of time. This results in a log-normal model, showing a significant cohort specific effect on the wastage behaviour. Extending this cohort analysis technique, together with double exponential smoothing forecasts, to future retention rates (1 - cumulative wastage rates), a long-term planning model is constructed to study the relation between expected yearly recruitment levels and the target manpower requirements for the future five-year planning horizon. While the idea and model developed here are generally applicable, the present computational results provide valuable decision supports for an actual case study, for CPHK in particular.