What is in the bathtub?

This is the first and most important question to ask in a system analysis: what does the bathtub represent to you, or to your organization, or even to a particular program? Think of the change you want to see in the world as represented by a bathtub.

What do you want to see more of or less of in the world? Are you trying to increase the volume of something in the bathtub (such as increasing the number of trees in the forest) or diminish the volume of the bathtub (such as decreasing the number of people in a city who are living on the streets)?

How does is this bathtub influenced by all the surrounding variables? For instance, let’s suppose you want to address poverty in your city. Your bathtub represents the number of people in your city who are living on the street. Before you can think about increasing or decreasing the ‘stock’ in this bathtub, you need to think about the flow. How do people find themselves in this situation? If you start brainstorming the intersecting stories and potentials, it probably will not take long before the ‘map’ starts looking very complex indeed.

In fact, the diagram will eventually look incomprehensible. As complexity theory suggests, it is virtually impossible for us to define a singular reason why any given person finds themselves in poverty. Indeed, the ’cause’ of poverty for any given person is as unique as the individual themselves. Therefore, you could potentially draw an infinite number of causal relationships in this map…and still not be able to pretend to understand poverty in any whole or comprehensive way.

And if you think about how people might ‘exit’ the waiting list for affordable housing — and what other aspects of the system are involved — the mental model for this map could grow to be infinitely complex, with an infinite number of factors, actors, or ‘nodes’ in the system. You could probably spend days speculating and drawing causative relationships between different parts of the whole system.

What is the lesson the analogy so far? The ‘bathtub’ you want to affect in the world is probably just as systemically complex as the bathtub in your house. In fact, it is likely even more complex and interconnected. Furthermore: the bathtub ‘out there’ does not have handy faucets and a drain plug you can easily turn to tweak water level, either.

The contents of your bathtub must be quantifiable. It needs to be something has a number or metric that can be counted — such as the number of trees per square kilometre in your forest or the number of people on a waiting list for affordable housing. Can’t come up with something countable? What would be a viable ‘proxy’ measure — something observable in the world — that would indicate you are achieving your objective? Put the proxy in the bathtub.

Beware of putting ‘immeasurables’ in your bathtub. Resist the temptation to use words that are technically subjective or otherwise empirically undefinable — such as ‘poverty,’ ‘wealth,’ ‘value,’ ‘engagement,’ or ‘capacity.’ Instead, ask: if we had more/less of this in the bathtub, what measurable difference would we see in the world?


Cite this page:
Shelley, James. (2020). 'What is in the bathtub?' (in System Thinker Notebook). Originally published on August 5, 2020. Accessed on October 28, 2020. Licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Permalink: https://jamesshelley.com?p=17090
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