To assess these, a questionnaire consisting of 40 items covering a broad ran­ge of participation motives has been constructed following the usual approach of reliability and structural analyses. 8 dimensions have been extracted yielding homogeneous sea les of sufficient reliability. The motive to earn monetary / mate­rial incentives is strong but not dominant, other factors related to the curiosity of seeing new product concepts or to the altruistic motive to help manufacturers to offer more sustainable and environment-friendly products. Furthermore, the motivational impact of three factors have been studied using a quasi-experimental 2*2*2 set-up: (1) high vs. low incentives to participate in the study. (2) the number of previously collected redeemable loyalty points (high vs. low) and (3) whether the respondent had already received a material incentive (= amazon voucher) in exchange to his I her points in the past.

The results indicate that there are no significant main effect of incentive on the participation motives, nor of the number of previously collected loyalty points. Ho­wever, several of the scales are significantly affected by the experience of having redeemed an incentive, although the effects are rather small. Having established the stability of the motivational structure as assessed by the questionnaire, further findings will be presented regarding the influence of different recruitment strate­gies on motivational structure of respondents. We believe that these findings will be relevant to evaluate and manage the quality and psychographic structure of online panels, particularly compared to offline market research and sampling. Lectures of social networks are strongly governed by physical.