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Another Voice: Daylight saving time reduces some criminal activity

By Amitrajeet A. Batabyal

At 2 a.m. on the first day of daylight saving time (DST), clocks move ahead by an hour, transferring daylight from the early morning to the evening by pushing sunrise and sunset back by an hour.

DST was first proposed by Benjamin Franklin to save money on candles by moving daylight from a time when very few were working in the morning to the evening, when many more were working. Although this energy-saving motivation has been touted as a rationale for DST, there is little credible evidence to show that DST actually saves energy. In addition, a 2012 poll showed that a majority of Americans think that DST is not “worth the hassle.”

What then does DST have going for it? Interesting new research by Jennifer Doleac and Nicholas Sanders shows that DST reduces outdoor criminal activity in general and robberies in particular. Why might the presence of ambient light affect criminal activity? Let us first think through the answer intuitively. By raising the likelihood of capture and the expected cost of criminal activity, increased light lowers the expected return from crime, and this ought to deter criminal behavior. This is the “reduced supply” effect.

On the other hand, the presence of more light may lead individuals to stay out later, thereby increasing both foot traffic and the probability of interacting with criminals. In turn, this lowers the cost of searching for potential victims by criminals and hence we also have an “increased demand” effect. Given these two opposite effects, what we would like to know is the net effect of DST on crime.

The persuasive quantitative analysis of Doleac and Sanders shows that robberies – where one comes face to face with someone who demands something, like a mugging – decreased by about 7 percent in the weeks after the beginning of DST. This positive result is driven almost entirely by the 27 percent decline in the robbery rate during the evening hours – the big commuting hours from 5 to 7 p.m. – when the number of available people upon whom one could commit a crime is the highest. 

These researchers also studied the impact of DST on other kinds of violent crimes such as aggravated assaults, rapes and murders, but the evidence here is either inconclusive or inconsistent.

The plausible finding about the deterrent effect of DST on robberies does not mean that we should make DST a year-round policy. What it does mean is that we now have to balance the positive crime-fighting effect of DST with the twin negative effects stemming from the hassle factor that Americans experience and the evidence that shows that DST does not conserve energy. The devil truly is in the details.

Amitrajeet A. Batabyal is the Arthur J. Gosnell professor of economics at the Rochester Institute of Technology but these views are his own.