Ah I see, so the incentive value is just too plain... people may not have the hope that they will get a large enough incentive to make it worthwhile. This is so

Ah I see, so the incentive value is just too plain... people may not have the hope that they will get a large enough incentive to make it worthwhile. This is something I hadn't considered... I like your suggestions, especially the first one with 50%. We used to have the incentive more competitive, the top 10 people who had the most friends signed up would get a free shirt, but once again that would mean you'd have to think more about your sharing and check back in. Very good insight!