A population consists of all the members of a group of interest. A sample is a subset of the population.
Stratified sample.
Practice makes perfect
A population consists of all the members of a group of interest. Since it may be impractical to examine every member of a population, a sample — a subset of the population — is sometimes selected to represent the population. The sample can then be analyzed to draw conclusions about the entire population.
Let's consider our situation.
The owner of a community pool wants to ask patrons whether they think the water should be colder. Patrons are divided into four age groups, and a sample is randomly surveyed from each age group.
Here, the population consists of the patrons of the community pool. The sample consists of the randomly selected patrons from each age group. Samples can be classified into different categories.
Members that are readily available or easy to reach are selected.
In our situation, the patrons are divided into groups based on their age. Then, the ones surveyed are randomly selected from each age group. This means that we have a stratified sample.
