Editing Sampling bias (section)

===The caveman effect===
An example of selection bias is called the "caveman effect". Much of our understanding of [[Prehistory|prehistoric]] peoples comes from caves, such as [[cave painting]]s made nearly 40,000 years ago. If there had been contemporary paintings on trees, animal skins or hillsides, they would have been washed away long ago. Similarly, evidence of fire pits, [[midden]]s, [[ceremonial burial|burial sites]], etc. are most likely to remain intact to the modern era in caves. Prehistoric people are associated with caves because that is where the data still exists, not necessarily because most of them lived in caves for most of their lives.<ref>{{cite journal |vauthors = Berk RA |title=An Introduction to Sample Selection Bias in Sociological Data |journal=American Sociological Review |date=June 1983 |volume=48 |issue=3 |pages=386–398 |doi=10.2307/2095230|jstor=2095230 }}</ref>