In a recent study for the National Bureau of Economic Research​ (NBER), four researchers looked at the effect of generous unemployment benefits on the local unemployment rate. They compared the unemployment situation in adjoining​ counties, which happened to lie in two different states that had different laws regarding the amount and duration of unemployment benefits.​ (Re-read the section on​ "A Natural Experiment of​ History" in Chapter 8 of the text to understand how the NBER research is based on a​ "natural experiment.")The authors of the NBER study found that the unemployment rate​ "rises dramatically in the border counties belonging to the states that expanded unemployment benefit​ duration" during the Great Recession.Why might this be​ so?Based on​ Hagedorn, Karahan, et​ al., "Unemployment Benefits and Unemployment in the Great​ Recession: The Role of Macro​ Effects." NBER working paper​ 19499, October 2013.