Voluntary Sampling  Voluntary samples are surveys where members of a population are invited to respond voluntarily.  Responses are not mandatory.

Examples  A radio show asks listeners to call in to share their opinions on a particular issue.  Government surveys where forms are mailed to the population, who may or may not partake in the survey.

Pros & Cons PROSCONS  Convenient to organize  Most responses will be from people who feel strongly about the subject  Usually does not represent the entire population equally  Biased and not as reliable as random surveys