As the costs and nonresponse rates of traditional, probability-based surveys seem to grow each year, the advantages of online surveys are obvious – they are fast and cheap, and the technology is ...

These results are consistent with the conclusion that non-probability samples yield data that are neither as accurate as nor more accurate than data obtained from probability samples.

Non-probability Sample: A sampling approach that does not confer every population member a known probability of selection, often necessitating additional statistical adjustments.

Neil Malhotra, Jon A. Krosnick, The Effect of Survey Mode and Sampling on Inferences about Political Attitudes and Behavior: Comparing the 2000 and 2004 ANES to Internet Surveys with Nonprobability ...