The effects of incentives on response rates, web completion rates and demographic and socioeconomic characteristics were investigated in a randomized experiment for a general population economic attitude survey. The experiment was conducted in two groups: 1) fresh cases from Address based sampling (ABS) postal addresses, and 2) recontact cases that were interviewed six months ago. The prepaid cash incentive condition was crossed with a set of Web-Mail survey contact strategies. While the fresh cases were contacted by Web-Mail concurrent or web-intensive contact strategies, the recontact cases were contacted by mail, concurrent or web-intensive contact strategies. Overall findings showed that incentives increased average response propensity without changing the covariance component of the nonresponse bias given the comparisons on a set of demographic and socioeconomic characteristics by the incentive condition. While the prepaid cash incentives significantly increased the web completion rates in the web intensive contact strategy for the fresh sample, they had a reversed effect in the concurrent strategy for the recontact sample.