Sampling and testing hypotheses
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 In a survey, a sample is a small selection of the population. Samples are less reliable but quicker, cheaper and easier to question than the entire population..
You should only use sampling when you have a large In a survey the population is every person who could be questioned..
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 鈥 'PoochChow' or 'CaneDine'.
- Bethan should use a sample 鈥 she cannot possibly ask everyone in the country.
- Matthew should not use a sample 鈥 it would be reasonable to ask all of his classmates.
- Stephen should not use a sample 鈥 he could check all the brands in the supermarket.
- Sian should use a sample 鈥 there are far too many dog owners to ask them all.