- Samples based on voluntary responses tend to over-represent certain portions of the
population. Voluntary responses are commonly from people with very strong opinions
(usually negative)
- A sampling scheme displays bias if the sample systematically favors certain parts
of the population over others. If certain parts of the population are overrepresented
in the sample, while others are underrepresented, then sampling bias exists.
Dr. Christina Hayes
Wilson 2-263
Department of Mathematical Sciences
Montana State University
Bozeman, MT 59717
phone: 406-994-6557
fax: 406-994-1789
christina.hayes@montana.edu
(Email will likely reach me faster than a phone call)
