As David Sirota points out in an excellent column about Shlaes, the New Deal and unemployment, her analysis of unemployment data has been discredited by a University of California historian. Sirota goes on to point out that under the New Deal, America experienced the second greatest drop in the percentage of unemployed recorded from 1932 through 2008. (Sirota is considering the New Deal as having ended in 1941, the year that WWII started.) The only greater drop occurred during the period of 1940 through 1944.
Why is any of this important? Because right now the Congress is considering how to stimulate the economy. Conservatives and Republicans argue that government projects won't work in reducing unemployment. They will be citing Shlaes's book in support of these arguments. Sirota's column is one small way to argue back.