The National Industrial Recovery Act extended the power reach of the statist.  It increased the size and authority of the Federal government.  The result was a 25% drop in industrial production over a six month period. 

Harold Cole and Lee Ohanian (UCLA) conducted a study in 2004 concluding that the great depression was extended by seven years because of government intervention.  Without that intervention, the free market would have corrected quickly.  The depression would have ended in 1936, but government intervention extended the depression to 1943.  Students have since been taught that the free market can't be trusted to avoid depressions.  However, the great depression was caused by tyrannical government and prolonged by tyrannical government.

Source: Liberty and Tyranny by Mark R. Levin