Pro-labor policies pushed by President Herbert Hoover after the stock market crash of 1929 accounted for close to two-thirds of the drop in the nation's gross domestic product over the two years that followed, causing what might otherwise have been a bad recession to slip into the Great Depression, a UCLA economist concludes in a new study.

"These findings suggest that the recession was three times worse — at a minimum — than it would otherwise have been, because of Hoover," said Lee E. Ohanian, a UCLA professor of economics.

The policies, which included both propping up wages and encouraging job-sharing, also accounted for more than two-thirds of the precipitous decline in hours worked in the manufacturing sector, which was much harder hit initially than the agricultural sector, according to Ohanian.

"By keeping industrial wages too high, Hoover sharply depressed employment beyond where it otherwise would have been, and that act drove down the overall gross national product," Ohanian said. "His policy was the single most important event in precipitating the Great Depression."