Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation’.

Giné et al. (2008)
Xavier Giné,Jonathan Zinman,Dean Karlan
Summary by 
Mark Egan

CARES was a voluntary commitment product to help people quit smoking. Smokers got a savings account in which they put their money for 6 months, after which they take a urine test. If they pass, their money is returned without interest. If they fail, the money goes to charity. The authors found those offered CARES were more likely to 3% points more likely quit smoking after 6 months.