Dr Grimes initially created an equation to express the probability of a conspiracy being either deliberately uncovered by a whistle-blower or inadvertently revealed by a bungler. This factors in the number of conspirators, the length of time, and even the effects of conspirators dying, whether of old age or more nefarious means, for those conspiracies that do not require active maintenance.

Source: Equation shows that large-scale conspiracies would quickly reveal themselves

The equation was compared to known conspiracies to validate it. Turns out most conspiracies will make themselves known pretty quickly.