Sampling and testing hypotheses

If you want to test the 'Boys are taller than girls', it is impossible to measure the height of every boy and girl in existence.

A sensible way around this would be to take a selection of boys and girls, measure their heights, and use this information to judge whether the statement is likely to be true or not.

This process is called .

You should only use sampling when you have a large .

Question

For each of the following scenarios decide whether it would be sensible to use a sample.

• Bethan wants to find out how many times people in Wales attend the cinema per week.
• Matthew wants to find out if people in his form class prefer burgers or chips.
• Stephen wants to know which brand of baked beans in his local supermarket is the cheapest.
• Sian wants to find out which breed of dog food is more popular among pet owners – 'PoochChow' or 'CaneDine'.
• Bethan should use a sample – she cannot possibly ask everyone in the country.
• Matthew should not use a sample – it would be reasonable to ask all of his classmates.
• Stephen should not use a sample – he could check all the brands in the supermarket.
• Sian should use a sample – there are far too many dog owners to ask them all.