Contrary to business rhetoric, studies reveal that that higher minimum wage levels do not force employers to lay off workers. In a study published in the Review of Economics and Statistics, economists Arin Dube, William Lester and Michael Reich compared counties adjacent to state borders, where one state raised the minimum wage and another did not, between 1990 and 2006. They found conclusively that raising the minimum wage had no impact on employment. A similar study by Alan Krueger - now the head of the Council of Economic Advisers - came to the same conclusion. The Obama White House also noted that Costco, the retail discount chain, Stride Rite, a children's shoe chain, and other firms have supported increasing the minimum wage, saying it reduces employee turnover and improves workers' productivity.