Inspired by the positive effects of incentives on mail survey response rates, researchers have started using incentives to increase response rates to Web surveys. The established best practice of presending cash incentives is difficult to implement in Web surveys, and studies suggest that its presumed effects might not be witnessed in Web surveys. In contrast, several studies have found that lotteries can significantly increase Web survey response rates. Some authors have argued that this could reflect the fact that Internet users have come to expect Web surveys to be associated with lotteries. An experimental study among university students found that the lottery influences the Web survey response rates, but there are indications that different subgroups might be more influenced by this incentive than others. The observed differences are interpreted along the lines of possible differences in the degree to which different respondent groups expect incentives in return for their participation.