The principal method used to develop the oral health workforce projections is mathematical simulation modelling, using the National Health Workforce Tool. The simulation model employed to generate the workforce supply projections is a dynamic stock and flow model.
A stock and flow model involves identifying the size and activity of the current workforce (stock) and sources of inflows and outflows from the stock (people entering and exiting the workforce), as well as looking at trends or influences on the stock and flows. To project future supply, the initial stock is moved forward based on expected inflows and outflows, allowing for the impact of trends and influences in the stock. The workforce is broken down into age and gender cohorts, and different flow rates are calculated by cohort and year for each of the input and output factors.
The oral health workforce projections used a dynamic version of the stock and flow approach. This means the stock of the workforce is affected by inflows and outflows to adjacent age cohorts within the stock, as well as external inflows and outflows. That is, each age and gender cohort receives inflows not just from graduates and migration (external flows), but also from people ageing within the model that move from one age cohort into the next. For example, someone moves from the 30 to 34 cohort into the 35 to 39 cohort. Similarly, each age and gender cohort has exits applied – exits as people leave the workforce altogether, and exits as a person moves into the next age cohort. This is an iterative calculation in each year over the projection period, and provides for a more realistic representation of labour dynamics. This provides for a more realistic representation of labour force dynamics. This process is represented in Figure 15.
There are four key inputs in the dynamic stock and flow model:
Migration (permanent and temporary)
Exits, which includes all permanent and temporary flows out of the workforce.
Calculation of the workforce ‘stock’ in the base year (2012) used the National Health Workforce Dataset (NHWDS): Dental practitioners data. The NHWDS combines data from the annual registration process for registered oral health practitioners, together with data from a workforce survey that is voluntarily completed at the time of registration.
The workforce stock is categorised into five-year age and gender cohorts.
Data from the Australasian College of Dental Schools (ACODS), the Department of Education, and the National Centre for Vocational Education Research (NCVER) was used to estimate the anticipated number of new and completing graduates, based on recent trends in the number of graduating students, the number of trainees currently in the system and their expected years of completion.
Table 4 shows the number of domestic and international graduates (current and projected) for each practitioner group to 2017. From 2017, graduate numbers are held constant in the model.
Table 5 shows data from the Department of Immigration and Border Protection used to estimate migratory inflows. Both temporary and permanent migration numbers in 2012 are held constant to 2025. To avoid double counting, the number of permanent migrants who had not previously held a working visa was used as the input into the workforce projections.
Estimates of exits are based on the number of permanent departures (retirements, resignations, deaths and migration) and temporary departures (absences from the workforce on a medium to long term basis, including leave without pay and maternity leave) from national registrations.