Supplemental Material, Kalleitner_online_supplement_(1) - What’s the Benefit of a Video? The Effect of Nonmaterial Incentives on Response Rate and Bias in Web Surveys

Supplemental Material, Kalleitner_online_supplement_(1) for What’s the Benefit of a Video? The Effect of Nonmaterial Incentives on Response Rate and Bias in Web Surveys by Fabian Kalleitner, Monika Mühlböck and Bernhard Kittel in Social Science Computer Review