Proving the benefits of diversity

I apply a self-conscious heuristic — let’s go with the Anglo-Saxon and call it a rule-of-thumb — that more diversity breeds more resilience. In most disaster contexts I do NOT have data or really much evidence that this assumption or principle or guess accurately fits the immediate problem-context. But I have seen enough data and evidence from analogous situations that I tend to make decisions that depend on the claim. (Such as here and here and here.)

Rigorous empiricists offer increasing evidence that takes us well-beyond inspired (or delusional) analogies. Late last week Nature, one of the most prestigious peer-reviewed journals, published, “Supply chain diversity buffers cities against food shocks“. The title states the claim. The paper organizes and analyzes data that persuasively demonstrates the claim.

The authors (two of whom I know), write, “For cities in the USA, the probability of an annual food supply shock S being greater than a shock intensity s, P(S > s) (see Methods), declines as the diversity D of a city’s food inflows supply chain increases … Using data for 284 cities and 4 food sectors, the annual probabilities of food supply shocks are calculated by measuring, for each city and food sector, the maximum food supply departure from the annual average during 2012−2015 (Methods). We utilize a total of 4,884 buyer–supplier subgraphs and 1,221 time series to calculate P(S > s) and D. Our results indicate that with greater supply chain diversity D, cities are more likely to avoid or resist shocks of increasing intensity (3%, 5%, 10% and 15%; Fig. 1a).”

It is an academic paper using scholarly language and calculus. The reasoning is, still, clear enough. Absolutely worth reading.