Statistics / Unit 5: Collecting Data
5.1 Populations, Samples and Census
Notes
The population is the entire group we want to learn about. A sample is the part of the population we actually collect data from.
- A census collects data from every member of the population. It is often too slow or costly.
- A parameter is a number describing a population. A statistic is a number describing a sample. Statistics are used to estimate parameters.
- Example: A principal surveys 60 of the 900 students. The population is all 900 students, the sample is the 60 surveyed, and the percent of the 60 who like the new schedule is a statistic.
Practice
A principal wants to know the opinion of all 900 students and surveys 60 of them. The population is:
The population is the entire group we want to learn about.
In a sample of 50 students, 20 own a pet, so $40\%$ own a pet. The $40\%$ is a:
It describes a sample, so it is a statistic.
A census differs from a sample survey because a census:
A census attempts to include everyone, but it can be costly and difficult to complete.
Ready for more? Take the Unit 5 test.