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A doctor wants to know how many hours the children of a town sleep.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A doctor wants to know how many hours the children of a town sleep. She asks the parents of the 60 children who visit her clinic in one week.
- What is the population?
- What is the sample?
- Is the sample fair? Say why.
Need a reminder? The key ideaShow
The population is everyone we want to know about. The sample is the few we ask. A fair sample gives everyone the same chance of being chosen. A sample that leaves out a kind of person is biased.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The population. All the children of the town.
Step 2. The sample. The 60 children who came to the clinic that week.
Step 3. Is it fair? No. Children who visit a clinic are often unwell, and they may sleep more or less than usual. Children who are well are left out.
A fairer way. Choose children by chance from the school lists of the town.
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