Definition
Representativeness
Representativeness is how well a sample reflects the relevant features of its target population.
Continue from this idea into connected AXIO math.
The small group should look like the big group in the ways that matter.
Boundary: A sample does not need to copy every detail of the population, but it must not systematically leave out important groups.
What it means
A sample is a small group used to learn about a bigger group. It should include the kinds of people or items that matter to the question. A large sample from only one corner of the population can still give a misleading picture.
Remember it
The small group should look like the big group in the ways that matter.
Example
To ask what the whole school thinks about lunch, sampling pupils from every year group and different lunch choices is more representative than asking only one sports team.
Watch for
A sample does not need to copy every detail of the population, but it must not systematically leave out important groups.
Common mix-up
A bigger sample may be more precise, but size alone does not make it representative.
Exact meaning
Representativeness is the extent to which the people or items in a sample reflect the characteristics of the target population that matter for the question. It depends on how the sample is selected and covered, not only on how large it is.