Sampling Fractions and Populations
The ratio of the sample size to the population is often irrelevant.
Survey research concerns taking samples of a target population. Using those samples, we can estimate the views of that population.
This article looks at sampling fractions and the issue of finite populations.
Sampling fraction
In a simple survey, the sampling fraction is the ratio of the sample size to the population size. For example: in a population of 56m adults, a simple random sample of 2,000 adults has a sampling fraction of 0.0036%.
There may be misunderstandings that sampling fractions measure how representative the survey is. In a recent Policy Exchange report, the methods section stated:
The sample consists of 820 respondents (484 currently employed and 336 retired; average age of current academics is 49 and of those retired is 70). Given the approximately 217,000 academic staff working in British universities in 2018–19, our sample is proportionately many times larger than a conventional opinion survey (typically a sample of 1,500 across a national population of 60m). As such our data has a good claim to being representative of the wider academic population even though, as with all opinion surveys, there is a margin of error in the results.
