Why Did the Average Duration of Unemployment Become So Much Longer?
This paper examines the causes of the observed increase in the average duration of unemployment over the past thirty years. The results indicate that more than 70 percent of the increase in the duration of unemployment over the past thirty years can be attributed to an increase in within-group wage inequality.
Link
http://www.newyorkfed.org/research/staff_reports/sr194.pdf