Injuries to a sample of 214 child skiers
Injured | Uninjured | Total | |
---|---|---|---|
Beginner | 20 | 60 | 80 |
Intermediate | 9 | 84 | 93 |
Advanced | 2 | 39 | 41 |
Total | 31 | 183 | 214 |
Are those sample data consistent with independence in the underlying population?
Explain that independence is a population property and would mean that the probability of injury was the same for all groups of skiers. We must use the sample to help assess whether there is independence in the population.
The randomness of the sample data means that the conditional proportions will not be equal even if there was independence in the population.
Independence is an important special case of the model that is worth testing.
The contingency table categorises a sample of 214 child skiers according to their skiing ability and whether or not they were injured.