Comparison of the<unk> to the exact binomial one-sided confidence interval with no positive samples In statistical analysis, the<unk> states that if a certain event did not occur in a sample with subjects, the interval from 0 to 3/ is a 95% confidence interval for the rate of occurrences in the population. When is greater than 30, this is a good approximation of results from more sensitive tests. For example, a pain-relief drug is tested on 1500 human subjects, and no adverse event is recorded. From the<unk>  it can be concluded with 95% confidence that fewer than 1 person in 500 (or 3/1500) will experience an adverse event. By symmetry, for only successes, the 95% confidence interval is . The<unk>  is useful in the interpretation of clinical trials generally, particularly in phase II and phase III where often there are limitations in duration or statistical power. The<unk> applies well beyond medical research, to any trial done times. If 300 parachutes are randomly tested and all open successfully, then it is concluded with 95% confidence that fewer than 1 in 100 parachutes with the same characteristics (3/300) will fail.
Rule of three 
USMLE Step 3
Garrod Lecture and Medal
Dispensing category 
Florida shuffle
Floor plate
Trance
Hangnail