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 test 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? With the longer duration of unemployment benefits, firms needed to keep wages high to attract people to work. This caused downward wage rigidity, leading to persistent higher unemployment. The longer duration of unemployment benefits encouraged those workers who were unemployed to seek work sooner to avoid having their skills diminish, which increased the time for job search, leading to higher unemployment The longer the duration of benefits, the lower the wages become that firms will offer new workers. This caused upward wage rigidly, causing unemployment to rise dramatically. All of the above.