A population is the entire group that you want to draw conclusion about.
A sampling frame is a list of all the items in your population. The specific group that you will collect data from. The size of the sample is always less than the total size of the population.
In research, a population doesn’t always refer to people. It can mean a group containing elements of anything you want to study, such as objects, events, organizations, countries, species, organisms, etc.
The difference between a population and a sampling frame is that the population is general and the frame is specific.
