who put no money down. Steven Levitt, co-author of Freakonomics, wrote about and approved of the website and its concept. StickK also appears in the [popular press] book More Than Good Intentions, where it is mentioned as an example of a type of commitment device that can be adapted to development programs in microsavings and health. According to Karlan, the company's name comes from 'stick'ing to it, and the second K is the legal shorthand for a contract. It also refers to carrot and stick. Further reading References Yale University Online companies of the United States