Copyright 2016 NPR. To see more, visit GREENE, HOST: We know there is growing income inequality in the United States. Incomes for the wealthy are rising faster than incomes for the poor. There's also new social science research that suggests the rich might also be getting richer for another reason. And to talk about that, we're joined by NPR's social science correspondent, Shankar Vedantam. Shankar, hello as always. SHANKAR VEDANTAM, BYLINE: Hi, David. GREENE: So even more good news for people with a lot of money. VEDANTAM: (Laughter) It appears so, David. This has to do with the cost of things that people buy. I was talking with Xavier Jaravel. He's a postdoctoral scholar at Stanford. He's just analyzed the prices of goods in department stores, drugstores and grocery stores - massive amount of data. He finds an important difference in changes in the price of goods purchased by wealthy people and by the poor. Here he is. XAVIER JARAVEL: I found that the products purchased mainly by the
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