Final answer:
A research by a Harvard professor found a trend toward greater income inequality in the United States in recent decades, focusing on the changing shape of American households and greater inequality of wages.
Step-by-step explanation:
A research by a Harvard professor on American participation in wealth inequality found that there has been a trend toward greater income inequality in the United States in recent decades. This trend is also observed in many countries around the world, although it has been more powerful in the U.S. economy. The research focused on two factors that contribute to the increasing inequality: the changing shape of American households and greater inequality of wages, often referred to as 'winner take all' labor markets.