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Rideshare apps like Uber and Lyft make it easier to get a ride instead of driving home wasted from the bar—but does this mean fewer people are driving drunk? The number of DUI offenses have dropped in Los Angeles and other cities since ride-sharing arrived on the scene, but police say there's no way to credit these companies for that change.
KPCC reviewed data covering the last five years of DUI citations from the California Highway Patrol. They found that the numbers peaked before Uber started operating in our city in April 2012 and have dropped during the last two years that Uber as well as Lyft entered the market.
LAPD Lt. Michelle Loomis told LAist that there was a slight decrease in DUI crashes from 2013 to 2014, and 2012 had an even larger decrease. However, she said "there’s no way we can measure how we can relate that to DUI arrests." Loomis said that a lot of things could have played into the drop in numbers like "more education" about DUIs and a change in "the way the public has viewed DUI driving."
In other words—as any statistician or data nerd worth their salt would tell you—correlation isn't causation. But that hasn't stopped Uber from trumpeting the correlation or other analysts from digging into the stats—with plenty of caveats.
In a blog post this spring, Uber estimated that the number of DUI arrests in Seattle dropped by 10 percent since their rideshare app came in that city. Uber writes, "This simple econometric study provides evidence that Uber’s network of safe, readily available rides have a meaningful and measurable impact on drunk driving in cities in which Uber operates freely."
Seattle Police Detective Drew Fowler told KPCC: “We have seen a decrease in the number of DUI arrests made. If part of that can be assigned to the introduction of Uber, fantastic. But I don’t think proving the veracity of that is going to be very easy to do."
The Washington Post reviewed the effects of rideshare companies on San Francisco, since all these apps first launched in the Bay Area. Using information from the San Francisco Police Department dating back to 2003, they mapped out on a graph that shows a peak of DUI arrests in the late 2000s, but a steady decrease of arrests when Uber launched their service in June 2010 and when other companies followed suit in the summer of 2012. You can see the graph here. However, they noted:
Again, caveats are in order. We've simply plotted arrests on a timeline here; we haven't adjusted for changes in the city's population, or bar scene, or the economy. Any number of other things may have changed in the city over the last few years affecting DUI arrests. It's possible police have changed how they conduct DUI stops and arrests, or that public pressure on them to crack down on DUIs has ebbed with time. Other changes in public transit service may have impacted alternative routes that bar-hoppers take home.
Blogger Nate Good, a Chief Technology Officer at an event ticketing company by day and a data nerd on the side, dug into DUI trends from Philadelphia's Uniform Crime Reporting system. He found that the average number of DUIs per month in Philadelphia decreased by 11 percent between April 2013 and December 2013, since companies like Uber came into the picture. He placed these statistics against the monthly average number of DUIs from January 2004 to January 2013, prior to the entry of the rideshare companies. He notes that he is a not a statistician and when he released the stats, he wasn't affiliated with Uber—but he is now in contact with them to get more info about different age groups using them in the Philadelphia area. "As the famous adage goes, correlation does not equate to causation," he wrote on this blog. "There can always be other things in play here that are affecting these DUI trends."
