A 'veil of uncertainty' is causing global market volatility

Global markets dropped after Apple CEO Tim Cook announced unforeseen sales declines for iPhones in China. Why is the Chinese economy so important to American business, and what's at the root of global market volatility? Diane Swonk, chief economist with Grant Thornton, talks to Judy Woodruff about trade tensions, data delayed due to the government shutdown and investors' "veil of uncertainty."