Define and describe one limitation of volunteer sampling.

Volunteer sampling refers to recruiting subjects who are willing to participate in the study. For example, the researcher could distribute leaflets and place an advertisement in a newspaper. The voluntary recruits will then contact the researcher.
One limitation of volunteer sampling is the biased sample produced. The volunteers might share psychological traits which differ from those who do not volunteer. For instance, these individuals might have higher levels of motivation or free time on their hand. This self-selection bias will reduce the representativeness of the sample.