I found this article which describes a bit more about what stickK.com plans to do. It still doesn’t reveal how they are going to solve the verification problem, but it sounds like they might be using something like a social network to do it — maybe your friends have to verify that you’ve met your goal. I’m just guessing though.

One thing I found puzzling is their business model:

Karlan said he, Ayres and Goldberg are committed to offering the Web site’s services free of charge and that they plan to make it profitable through advertisements and product tie-ins — promoting books that help people lose weight, for instance.

Of course these are sensible things to do, but I don’t know why stickK.com doesn’t want to charge directly for its services. It’s providing something valuable: motivation to achieve something. People will be willing to pay for that. It is true that some people might realise that they can just bypass the site and make private arrangements to achieve the same effect, so stickK.com faces competition from such agreements and can’t set a too high price. For example I can just make a contract with my mother that says I have to pay her if I don’t lose weight. However, stickK.com can offer something that my mother possibly can’t: subgame perfection. That’s a nerdy way of saying that if I didn’t lose weight, my mother might feel sorry for me and not force me to pay what I had agreed to pay. Anticipating this, I’ll have less incentive to lose weight in the first place, and the contract doesn’t work. An impersonal profit-maximising business will not suffer from this problem, and people will be willing to pay a price for that.

I also realised that this experiment could produce some really interesting data, like how much per kg are people willing to pay for the motivation to lose weight? Or what’s the difference in amount paid between people who achieved their goals and those who didn’t? In other words, what’s the value of willpower?

[Edit: typo]