But there are many cases where the data tends to be around a central value with no bias left or right, and it gets close to a "Normal Distribution" like this:
How many people need to be exposed to something to harm one patient.If 52 people are exposed to awesomeness, 1 will become awesome. 52 is the number needed to be awesome.If 13 people are exposed to an omen, one will become jinxed. 13 is the number needed to jinx.Sorry if my examples are too weird .-.