When thinking about what works in education, we naturally look for approaches that are supported by evidence.
However, not every intervention will have been subjected to rigorous research. Does this mean that those interventions should be discounted?
Some people would say that the absence of evidence is not evidence of absence. I would agree with this, and yet I also understand why some people don’t like such arguments.
Consider the analogy of Russell’s teapot, formulated by the philosopher Bertrand Russell (1872-1970). He wrote that if he were to say that a teapot, too small to be seen with a telescope, was orbiting the Sun somewhere between the Earth and Mars, he should not expect anyone to believe him just because his assertion could not be proven wrong.
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In that sense, I agree that claims should be clear and verifiable - but that also holds for claims of negative effects. Without evidence, we can’t draw firm conclusions that something either works or does not work.
Education research: the opportunity cost
So, in the absence of evidence, how do we decide if an intervention is worthwhile? One thing people often refer to here is the “opportunity cost”.
In economics, this means the benefits you have to give up when you choose from a number of alternatives: committing to one thing means missing out on what is offered by the other options that you forgo.
If you think about this in financial terms, it is quite straightforward: when you have limited funds, you can only buy a certain number of items, so you need to determine which purchase matters the most.
But in education, things aren’t quite so simple, as there is often no clear way to calculate cost.
For instance, time is often mentioned as a cost. And yes, availability of time is an enormously important variable in teaching and learning - but how do you accurately weigh the costs and benefits of spending your time in one way versus another?
You could go to a Saturday conference as a professional development opportunity to improve your practice. Yet, if you had spent that time going out with friends to do something you enjoy, the resulting wellbeing boost might mean that you will teach better as a result. Alternatively, you could have produced some new worksheets during the same time, which will reduce your workload later that week.
The costs and benefits of such activities are highly contextual, and not always a completely transparent transaction, as buying a loaf of bread would be.
To complicate matters further, you also have factors such as so-called “sunk costs”: those that have already been incurred and cannot be recovered.
In theory, sunk costs should not influence our present or future decisions, but they can be hard to disregard. When you’ve spent hours rewriting curriculum statements, of course, you want to use them, whether they are proven to be beneficial or not.
On the face of it, making decisions on the basis of opportunity costs seems to be a reasonable position. But I worry that when people give “opportunity cost” as a reason not to do something in education, what they are really doing is expressing a preference based on incomplete information. They are incorrectly assuming complete transparency of costs for everyone and relying on humans being rational actors who will always optimise the benefits. This simply isn’t realistic.
In the end, what we are talking about is what choices you find more useful than others. Of course, opportunity costs can be considered, but this should be done in a considerate way, not as an easy slogan that really translates to “I prefer something else”.
Christian Bokhove is an associate professor in mathematics education at the University of Southampton and a specialist in research methodologies
