Collecting Data: Populations and Samples
In 6th grade statistics, a population is the entire group being studied, and a sample is a smaller representative subset of that population. A survey asks questions to collect data from a sample when polling the entire population is impractical. For example, to learn what 500 students prefer, surveying a sample of 50 gives reliable results much faster. This foundational concept, taught in Reveal Math, Course 1, Module 10, underlies all statistical reasoning about drawing conclusions from data.
Key Concepts
Once you have a statistical question, you need to collect data to answer it. Population: The entire group of people or objects you want to learn about. Sample: A smaller, representative part of that population. Survey: A method of asking questions to collect data from a sample.
Common Questions
What is the difference between a population and a sample in statistics?
The population is the entire group you want to learn about. The sample is a smaller subset of that population that you actually survey or measure. The sample represents the population.
Why do we use samples instead of studying the whole population?
Studying every member of a large population is too expensive, too time-consuming, or impossible. A well-chosen sample gives reliable information about the population at a fraction of the cost.
What is a survey in statistics?
A survey is a method of collecting data by asking questions to members of a sample. The answers are used to draw conclusions about the larger population.
When is it appropriate to study the whole population instead of a sample?
When the population is small enough to be studied completely — for example, recording the test scores of all 25 students in one class — you can use the entire population without needing a sample.
What makes a sample representative?
A representative sample is chosen randomly so that every member of the population has an equal chance of being selected. Biased samples (like only surveying friends) do not represent the whole population.
When do 6th graders learn about populations and samples?
This is covered in Module 10 of Reveal Math, Course 1, in the Statistical Measures and Displays unit.