Comment on 'What is a 'broad intervention' and what is a 'narrow intervention'? Are we confusing ourselves?'

Abstract

Comment by Owen Cotton-Barratt - Thanks Rob, I think this is a valuable space to explore. I like what you’ve written. I’m going to give an assortment of thoughts in this space. I have tended to refer to the long- vs short- path to impact as “indirect vs direct”, and the many-paths-to-impact vs few-paths-to-impact as “broad vs narrow/targeted”. I’m not sure how consistently these terms are understood. Another distinction which comes up is the degree of speculativeness of the intervention. There are some correlations between these different distinctions:

• Indirect interventions have more opportunities to be broad than direct ones.
• Indirect interventions are typically more speculative than direct ones.
• but broad interventions are often more robust (less speculative) than narrow ones. I think it’s typically easier to get a good understanding of effectiveness for more direct and more narrow interventions. I therefore think they should normally be held to a higher standard of proof – the cost of finding that proof shouldn’t be prohibitive in a way it might be for the broader interventions. I’m particularly suspicious of indirect, narrow interventions. Here there is a single chain for the intended effect, and lots of steps in the chain. This means that if we’ve made a mistake about our reasoning at any stage, the impact of the entire thing could collapse.