1) Identify the type
For each situation, decide whether the quantity describes:
- Population: the entire group being studied.
- Sample: a smaller part taken from the population.
- Parameter: a numerical value that describes a population.
- Statistic: a numerical value that describes a sample.
2) Use the wording clues
Ask two questions:
- Is it about all individuals or only some?
- All = population or parameter
- Some = sample or statistic
- Is it a number or a group?
- A group = population or sample
- A numerical description = parameter or statistic
3) Match the label
- If the statement names the whole group, label it population.
- If it names a subset, label it sample.
- If it gives a number describing the whole group, label it parameter.
- If it gives a number describing a subset, label it statistic.
4) Simplify the final answer
When an exercise asks for the final response, give only the correct label or exact simplified value. If a number is involved, make sure it is written in simplest form.
5) Check your work
A quick check is to ask: “Does this value come from everyone or just from the sample?” That usually determines whether it is a parameter or statistic. Also check whether you are identifying a group or a numerical summary.