| Tranona |
| (regular) |
| 15/05/2008 09:40 |
Re: "Liferaft" is it needed for coastal cruising in UK
|
Pedant
Probability is the ratio of events to sample (or population) size. You can express it as a ratio (x in y) or if you have a £2 calculator from Tescos you can turn it into a percentage. The concept and meaning is exactly the same.
So if there are 2 incidents each year and 10000 voyages, the probability expressed as a percentage is .0002%. If it halves next year to 1 and voyages stay the same it is .0001%. Both are close to zero. If the number of voyages halves to 5000 and there are two incidents the percentage rises to .0004%, still close to zero.
The number of incidents is not related to the number of voyages or number of miles. They are not randomly distributed across the population, but only occur in a narrow range of specific circumstances.
None of the key conditions for statistical analysis using probabilities therefore exists.