A statistical method of drawing representative data by selecting people because of the ease of their volunteering or selecting units because of their availability or easy access. The advantages of this type of sampling are the availability and the quickness with which data can be gathered. The disadvantages are the risk that the sample might not represent the population as a whole, and it might be biased by volunteers. For example, a study to determine the average age and sex of gamblers at a casino that is conducted for three hours on a weekday afternoon might be overrepresented by elderly people who have retired and underrepresented by people of working age. Also called accidental sampling.