The offset hypothesis predicts consumers adapt to innovations that improve safety by becoming less vigilant about safety. Previous tests have used aggregate data that may confound the effect of a safety policy with those consumers who are most affected by it. We test the hypothesis using...

In the face of rising congestion on the nation's road system, policymakers have explored ways to reduce travel delays. One approach has been to allocate reserved lanes - called high-occupancy-vehicle (HOV) lanes - to vehicles carrying two or more people. A recent innovation is to allow solo...