As explained by Janet Yellen (the former chair of the Federal Reserve) and various other economists with wide-ranging political views: "The most important factor determining living standards is productivity growth, defined as increases in how much can be produced in an hour of work. Over time, sustained increases in productivity are necessary to support rising incomes." For as far back in time as federal data exists, average labor productivity and worker compensation have risen at about the same rate except for several years on both sides of the Great Recession.