But if the participants are limited to people who are motivated solely by participating in research, wouldn't that add significant bias to that research?
Nonetheless, much of psychology research conducted in the US has made do with ridiculous sampling bias - the US college student is anecdotally considered to be the most-studied population in the world.
Nonetheless, much of psychology research conducted in the US has made do with ridiculous sampling bias - the US college student is anecdotally considered to be the most-studied population in the world.