Kanban, System Archetypes and Limits to Success

In a previous post I introduced the idea that Kanban can play a role in Systems Thinking and understanding System Archetypes. In this post I’ll describe system archetypes in some more detail, and describe the Limits to Success archetype.

Balancing Feedback

Balancing feedback will stabilise a system’s behaviour. For example a thermostat is a balancing feedback system where the temperature is measured, the difference from the desired temperature measured, and a heating or cooling device adjustment made accordingly. This can be depicted as below, with the B identifying the loop as balancing. When the temperature is higher than the target, then the adjustment is to generate cold air. When the temperature is lower than the target then the adjustment is to generate hot air.

Reinforcing Feedback

Reinforcing feedback will amplify a system’s behaviour. For example a bank account is a reinforcing feedback system where you have an account balance, onto which an interest rate is applied, and as a result you have interest paid to increase the balance (assuming your bank pays you interest). This can be depicted as below, with the R identifying the loop as balancing. As the cycle continues, more and more interest is paid, continually increasing your account balance. Conversely, when you have a negative account balance, your bank might apply a charge, which is deducted from your balance (much more likely). This cycle will continue as your account goes into increasing debt.

Delays

What makes systems complex is that there are often delays in the feedback loops. Delays separate cause and effect over time which often leads to instability and oscillation. For example, how many times have you been in the shower and tried to adjust the temperature, only to find the water suddenly get too hot or cold? This is due to a delay in the action of adjusting the temperature, and the temperature actually changing. As a result we tend to over-adjust and get burnt or chilled.

Archetypes

Most systems are not as simple as these examples, and consist of combinations of balancing and reinforcing feedback loops with different delays. However, a system’s particular structure will result in its behaviour being constant over time, and systems with similar combinations result in similar behaviours. These patterns which cause similar and recognisable system behaviour are known as system archetypes.

Being able to recognise system archetypes helps to identify the cause of behaviours, and gives insight into how to break (or encourage) the archetype to our advantage. Let’s take a look at an example.

Limits to Success

The Limits to Success archetype can be depicted as below.

To improve performance of a system, more efforts are made, which do lead to the anticipated improvements, creating a reinforcing loop. However, after some time the performance reaches a limit and resistance creates a balancing loop, leading to the performance levelling off, declining or even crashing.

Recognising this archetype leads to the understanding that when the systems resists, or pushes back on attempts at improvement, then rather than continuing to push the reinforcing loop, and increase efforts or do the same thing better, we should look to remove the limits by adjusting the system design to delaying the balancing loop. In other words, deal with the limits before the system does. The system’s limits will result in a worse outcome.

A Kanban System can help to cope with Limits to Success in a couple of ways. Firstly, setting explicit Work in Process limits is a way of directly limiting the system before the system does so itself, avoiding the decline or crash in performance. Secondly, gaining transparency of the work and the workflow is a beginning to learning what the cause of the limiting factor is. Visualising any bottlenecks or impediments gives a good indication of where to start looking to make changes in the system design.