A paid or incentivized survey is a type of statistical survey where the participant is rewarded through an incentive program, generally entry into a sweepstakes program or a small cash reward, for completing one or more surveys.
A paid survey is used to collect quantitative information about the participants' personal and economic habits set against their particular demographic. Incentivized surveys are considered to be more likely to catch a wider and more representative range of respondents compared to unincentivised surveys. YouGov in the United Kingdom say
"Respondents receive a small incentive for completing YouGov surveys. The purpose is to ensure that samples are as representative as possible, and that responses are not tilted towards those passionately interested in the subject of the particular survey.”
Legitimate surveys are usually unpaid (as with Gallup poll) or incentivized (as with YouGov); surveys where the respondent must pay or purchase products to join a panel are generally scams, as are sites that disappear before paying the participants. Legitimate surveys do not need credit card information from respondents.
Article source: http://en.wikipedia.org/wiki/Paid_survey
