Strategic behavior in repeated voluntary contribution experiments

We conduct a repeated VCM (voluntary contribution mechanism) experiment using the strategy method. We compare a partner and a stranger design and find that participants in the partner treatment provide (i) higher initial contributions, (ii) higher contributions on average over all periods, and (iii) contributions that do not vary more strongly with past contributions than participants in the stranger treatment. We conclude from our evidence that strategic motives can account for a large share of the treatment differences typically observed in this literature.