What's A 'Chained' CPI?

A plan put forth by a group of senators known as the "Gang of Six" looks like it could be a solution to solving the nation's impending debt ceiling problem. Among the ideas in the plan is trimming the deficit by changing how the country calculates inflation through using something called a "chained consumer price index." Michele Norris speaks with Robert Greenstein, the president of the Center on Budget and Policy about how this change will work.