Sampling and Observational Studies
This lecture series discusses the studies conducted using surveys. You can use surveys to obtain information about a group of people, but it can be impossible to survey each person if the group is very large. The limited number of people surveyed is called a sample. The way a sample is selected can affect the outcome of a study and its validity. Watch the videos and complete the interactive exercises.
Practice
Identify the population and sample - Answers
1. The population is all of the vehicles that pass through the lane with the camera; the sample is the group of every tenth vehicle that passes through the lane.
2. The population is all adult patrons of the library; the sample is the 
patrons selected.
3. The population is the parents of the pediatrician's patients; the sample is the 
parents of patients selected.
4. The population is everyone listed in the city phone directory; the sample is the 
people selected.