The Historic 1940 John Kerrich 10,000-Flip Experiment
During World War II, South African mathematician John Edmund Kerrich was interned in a camp in Nazi-occupied Denmark. To demonstrate the Law of Large Numbers to fellow internees, Kerrich flipped a single coin 10,000 times by hand, manually recording the cumulative running totals:
| Trial Milestone (N) | Observed Heads | Observed Heads % | Deviation from 50.0% |
|---|---|---|---|
| 100 Flips | 44 | 44.00% | -6.00% |
| 500 Flips | 255 | 51.00% | +1.00% |
| 1,000 Flips | 502 | 50.20% | +0.20% |
| 2,000 Flips | 1,013 | 50.65% | +0.65% |
| 10,000 Flips (Final) | 5,067 | 50.67% | +0.67% (1.34σ) |
Kerrich's final result of 5,067 heads falls well within the expected 95% confidence interval ($\mu \pm 2\sigma = [4,900, 5,100]$), representing an empirical variance of $z = (5067 - 5000) / 50 = +1.34\sigma$.