How should we think about the transferability of ideas and methods? If something works in one lace and one time, how do we know if it, or some variant of it, will work in another place or another time?

This – the transferability question - is one that many organisations face: businesses, from retailers and taxi firms to restaurants and accountants wanting to expand to other regions or countries; governments wanting to adopt and adapt policies from elsewhere; and professions like doctors, wanting to know whether a kind of surgery, or a smoking cessation programme, will work in another context.

The question is cast in a new light by the accumulation of evidence of all kinds, by ubiquitous data, and new tools that can automatically synthesise knowledge. We bother with evidence because of an assumption that it is in some senses transferable. Science would fall apart if chemistry and physics meant different things in different places, and usually we can be confident that if a medical procedure works with one kind of human it will work with others. The premise of ‘evidence-based policy’ is that evidence gathered in one context will be relevant to action in others.

So, the question is not straightforward, and although there is some academic literature on transferability, there is no simple formula that can tell you how transferable a model is. In this report, the author draws on this literature to suggest not so much a generalisable method, but rather an approach that starts by asking four basic questions of any promising idea:

1. Spread: has the idea already spread to diverse contexts and been shown to work?
2. Essentials: do we know what the essentials are, the crucial ingredients that make it effective?
3. Ease: how easy is it to adapt or adopt (in other words, how many other things need to change for it to be implemented successfully)?
4. Relevance: how relevant is the evidence (or how similar is the context of evidence to the context of action)?