Simple Workforce Model and game.

This model is a simplified version of a typical workforce planning model, for which System Dynamics is a good (quite possibly, the ideal) modelling solution, its capabilities match the degree of aggregation and time dimension that are indicated.

Typically, the challenge for workforce planners is this: how to decide how many places to offer on training programmes (including degrees) , given assumptions about

  • future workforce required
  • existing workforce
  • turnover and retirement rates
  • participation rates
  • time taken to train (and recruit) students
  • rates of non-completion of training

In this example, an added factor is that in the workforce of interest (specialist doctors) there are targets (based on safe and legal working practices) for people at two different stages in their career

  • middle grade doctors (who work, mostly in hospitals, on a rota system)
  • consultants (whose work pattern includes the need to be ‘on call’)

In fact, this is a simplified version of an actual model, implemented at a time when the demand for middle grade doctors was rising faster than the need for consultants, resulting from changes in employment law. This generated some interesting dynamics.

In our client’s model, there were many more inputs that could be varied. To make it simpler for the website, in this version, which has been fictionalised (as far as we know, no specialism has these exact parameters) we tell you the main assumptions (how long it takes to train, drop-out and turnover rates), and provide you with only one decision variable which is to determine the annual intake to training programmes. As you vary this number (by drawing on the graph) you can see instantly the impact on the workforce, over a 30 year period.

How to Use the Model


Every System Dynamic model’s behaviour is determined by its structure, please click through ‘the story’ to find out.

To be reminded about the structure, click ‘model’.

To get started, click Run. Lines should appear on the graph. To view the outputs in more detail, as numbers, click ‘figures’.

The solid lines are the target numbers for each of ‘middle grade doctors’ and ‘consultants’.

The dotted lines show the projected workforce (based on the annual intake figure). You want to get the dotted lines to track the solid lines (as closely as possible).

To change the intake numbers, simply draw on the graph (the line will change in five-year chunks). The rest of the graph should update instantly. If this stops happening, select ‘reset’ or refresh your screen (press the F5 button).

One measure of success is the size of the gap between each dotted line and its target. This produces a single score, at the top of the graph. You want as low a score as possible. Under 220 is very good. We have not yet seen a score under 200.

Things to Try

  • Try to get the middle grades line above (but not too far above) the target as early as possible and keep it there, always slightly above; what happens to consultants?
  • Try to get the consultants line as close as possible to the target line: what happens to middle grades?
  • Bearing in mind that this resembles a real task we were once set, what does the model tell you about the task itself?

Find Out More

This model was built using Stella Architect (c) software.

If you would like to find out more about how a System Dynamics model might help you think through a workforce challenge, please contact us.

If you would like to learn how to build models using this software, we can provide training. Further details here.

We welcome your feedback about any aspect of this model.