PolitiFact: In Uber fight, statistics get twisted like a bad wreck


An Austin City Council member made a honk-the-horn statement about passenger assaults as she advocated for voter approval of a proposition that would shrink what the city requires in background checks of drivers who work with ride-hailing services.

Council Member Ellen Troxclair opened by saying “ride-sharing is safe” during her appearance at an April 10 forum hosted by the League of Women Voters of the Austin Area. Troxclair, who represents District 8 in Southwest Austin, elaborated: “The truth is, if you look at the statistics, based on when TNC’s came to town and today, you are about nine times more likely to be assaulted by a taxi driver.” TNC means a transportation network company summoned through a cellphone app.

To our request for Troxclair’s backup information, her aide Michael Searle emailed a document he said Troxclair received from the Austin Police Department chief of staff, Brian Manley, listing all reported complaints to the police about assaults in taxi cabs or ride-hailing service vehicles since 2014.

Manley’s email also included a cautionary note about making safety comparisons based on the raw counts — a note he re-sounded when we asked him about the council member’s “nine times” analysis. His email to Troxclair’s office said: “Keep in mind these are only allegations of a crime, not cases that have been prosecuted,” he said. “Also, it is hard to say whether there are more allegations against cab drivers than TNC drivers because we don’t know how many rides each provider gave in a given year so we cannot come up with a rate, only the raw number.”

The document lists 37 reported incidents from Feb. 26, 2014, through Jan. 21, 2016: 14 complaints about cabs, 21 complaints tied to vehicles driven for Uber or Lyft and two complaints related to “independent” ride-hailed vehicles. Each entry indicates a crime ranging from assault “sexual nature” to sexual assault to rape.

Uber has said it routinely offered rides in Austin starting in June 2014. But it wasn’t until October 2014 that the council gave permission to the Uber and Lyft companies to operate, effective a month later.

If we limit our focus to the 15 months through January 2016 that taxi cabs and ride-hailing services each rolled with city permission, the count of cab-connected assault complaints decreases to six. Shrinking the time frame leaves unchanged the 23 assault complaints the department lists as related to ride-hailed vehicles.

So, how did Troxclair reach her conclusion about the chances of an Austin assault being nine times higher in a cab?

Searle said Troxclair reached her “nine times” conclusion by dividing the 14 cab-connected complaints since June 2014 by 913 city-issued cab permits (getting 0.015) and comparing that with what you get from juxtaposing the 23 ride-hailing complaints versus 15,000 ride-hailing service drivers in Austin (or 0.0015) — which actually suggests a 10-fold difference.

We ran Troxclair’s equation and statement past experts on statistics, each of whom flinched.

Rachelle Wilkinson, an adjunct professor of statistics at Austin Community College, said the calculations offered by Troxclair aren’t valid ways to gauge the relative incidences of sexual assaults. It’s “comparing apples to oranges (number of sexual assault reports to number of drivers),” Wilkinson said by email. “A much more valid way to look at the data would be to compare the sexual assault reports to the number of rides given — NOT the number of drivers. Taxi drivers tend to drive as their profession or job whereas ride-hailing drivers often do it on the side.”

That is, the number of rides “given by taxi drivers is likely much higher (per driver) than the number of rides given by ride-hailing drivers (per driver),” Wilkinson wrote, adding that ride counts didn’t appear to be part of Troxclair’s backup. Also, Wilkinson suggested, the probability of such assaults appears to be extremely small whether riding in a taxi or a ride-hailed car, she wrote.

Carol Gee, a St. Edward’s University math professor, similarly said by email that from the perspective of a passenger seeking a safe ride, “it is likely more appropriate to measure safety by the number of incidents per trip, rather than the number of incidents per driver.”

Our ruling:

Troxclair said statistics show “you are about nine times more likely to be assaulted by a taxi driver” in Austin than a driver for a ride-hailing service.

This claim shakes out to dividing oranges into apples and getting grapefruits — a ridiculous notion.

This leaves the “nine times” statement incorrect and ridiculous. Pants on Fire!



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