Why one weak link can hold back an entire economy

Economist Michael Kremer named his theory after the faulty O-ring that destroyed the Challenger space shuttle: when production requires many tasks to go well, one unreliable step drags down the value of everything else, no matter how skilled the other workers are. The model helps explain why poor countries can stay poor even as individual workers improve, and why skilled people cluster together.

— Michael Kremer, The O-Ring Theory of Economic Development — Quarterly Journal of Economics, 1993