Emails (excerpted), Michael Searle, chief of staff to Ellen Troxclair, Austin City Council member, District 8, April 12 and 14, 2016
4:09 p.m.
Thank you for the question and for following up to check the veracity of the statement. Attached I have included a report that was shared with our office by APD in January. It includes all complaints related to sexual assault by both TNCs and taxi cab drivers since 2014.
The stat she provided is a response to the presumption that a fingerprint background check will protect riders from sexual assault. If the argument and assumption is that it is the fingerprint background check which prevents future sexual assault, then calculating the statistic as it relates to the number of background checks conducted (whether fingerprint or not) seemed to be the appropriate approach. And she explains the calculation in the subsequent statement after the one you have bolded and underlined.
Since 2014, according to APD, there have been 14 alleged sexual assaults by taxi drivers and 24 by TNC drivers. If the estimate is that there are 15,000 TNC drivers, subject to name-based background checks and there are 913 cab permits, subject to fingerprint background check, then you are 9 times more likely to be assaulted by a cab driver than a TNC driver in Austin.
Let me know if you have any questions about how we calculated that.
Michael Searle
Chief of Staff, Councilmember Troxclair
Austin City Council, District 8
On Tue, Apr 12, 2016 at 2:25 PM -0700, "Selby, Gardner (CMG-Austin)" <wgselby@statesman.com> wrote:
Got it, thanks. Did the department or council member adjust for the amount of time each person drives a Uber versus the hours or days each driver drives a cab?
g.
4:28 p.m.
No. That data was not provided for either the taxis or the TNCs
5:15 p.m.
The document was provided by APD Chief of Staff Brian Manley. Below I have included the email from him to our office. As far as the calculation, I did that. It is the number of sexual assaults divided by the number of drivers.
-M
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Please find attached the information you requested on sexual assault allegations against cab drivers and TNC drivers. Keep in mind these are only allegations of a crime, not cases that have been prosecuted. 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.
Let me know if you have any questions.
Thanks,
Brian
10:43 a.m.
April 14, 2016
The equation you are using is exactly how I calculated it.
The # of cab permits came directly from ATD Staff and they should be able to confirm that. …
The # of TNC drivers came from a few sources, you can contact Jennifer Mullin with Uber to confirm. ...
But also, below I included the link to public testimony in December related to the TNC ordinance. Joseph Kopser, CEO and co-founder of Ride Scout cites the 15,000 number.
http://austintx.swagit.com/play/12172015-590/0/
Item 75 (Part 3) - 1:28
1:28 p.m.
I want to make sure to point out a couple things. First, she qualified her statement. She said, “when you look at the number of taxi drivers and the number of TNC drivers and the number of complaints that APD has received over that time, you are about nine times more likely to be assaulted by a taxi driver." She appropriately identified the data points she was referencing in making her statement. The responses you have shared from the two statisticians aren’t responsive to that context.
CM Troxclair’s quote was a response to the claims about fingerprinting, as it relates to public safety and sexual assault. In other words, you could say “there is a 9 times higher prevalence of sexual assault amongst fingerprint background checked taxi drivers than name-based background checked TNC drivers.” The variable at play is the background check, not the number of rides or drivers.
Response to Dr. Hersh below…
...
(HERSH) She also claims that there are 15,000 TNC drivers but many TNC drivers only work as a TNC driver for a very short period of time. There has never been a point where there were 15,000 people working as TNC drivers at the same time.
· From the data we have about number of drivers from Uber and Lyft, there are at least 15,000 active TNC drivers in Austin. I assume you will call them and confirm those numbers. Of course, they are not all on the road at the same time just as all 913 taxi drivers are not on the road at the same time. All 15,000 drivers have been subject to a background check that does not include a fingerprint. The safety claim by the proponents is NOT that, “the more drivers that are on the road at the same time, the less safe riders are from sexual assaults.” But rather the claim is, fingerprint background checks as opposed to name-based checks, provide a safety benefit by screening out potential drivers who commit sexual assaults. To check the validity of that claim, you must compare the number of assaults to the number of background checks.
…
(HERSH) Another serious issue in the statement is the fact that unlike taxi drivers who work much closer to full time (40 hours a week), TNC drivers only work as drivers part time. So looking at the number of assaults over the number of drivers to compare the probability of an assault is completely flawed.
· Again, nobody is making the argument that the amount of time, in total and/or per driver, is a threat to public safety. We do not have that data and it is not relevant to the argument.
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