Sampling and testing hypotheses

Silhouette of a crowd of boys and girls standing together

If you want to test the hypothesis '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 sampling.

You should only use sampling when you have a large population.

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.