#161
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visibility of DRL
On 4/9/2019 7:12 AM, jbeattie wrote:
snip Yes, I turn on my front flasher and say "f*** that, I'm going for it!" Then I start racing down the middle of the road, going the wrong way -- "I'm king of the world!" And with my helmet, it's no holds barred! Exactly. You're the prime example of risk-compensation. But seriously, you experience risk-compensation without even being aware of it. With a DRL, and with good lights in general, I know that vehicles are much more aware of my presence and less likely to exit a parking lot or a side street across my path. When I'm riding with only my dynamo light I know that I'm much less conspicuous so I ride differently. You often don't realize the risk compensation you engage in. https://www.theguardian.com/science/2016/jan/24/bike-helmet-appetite-danger |
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#162
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visibility of DRL
On 09/04/2019 10:12 a.m., jbeattie wrote:
On Tuesday, April 9, 2019 at 6:39:51 AM UTC-7, sms wrote: On 4/8/2019 6:19 PM, Jeff Liebermann wrote: The problem with DRL is that anyone can see that the light is flashing or not flashing. Everyone in the test group knows that they have a functional device and everyone in the control group knows that they don't have anything to test. Expected results soon turn into actual results. In other words, there's no way I could arrange a double blind study for DRL safety and the results will tend to favor the expected results. Another issue is that the group with the DRLs will be taking more risks. It's called " “risk compensation." In the Odense study, the results would have been skewed by risk compensation. If all the riders had somehow been forced to take the same risks, the conclusion would have been different, with the riders using DRLs having even fewer incidents. Yes, I turn on my front flasher and say "f*** that, I'm going for it!" Then I start racing down the middle of the road, going the wrong way -- "I'm king of the world!" And with my helmet, it's no holds barred! Yeah, I find that pretty ludicrous. I understand risk compensation. My kid does things on a snow board with a helmet that he wouldn't if he weren't wearing one. But DRLs on my bike? I don't think so. The safety mavens around here with their five flashers and three headlights, flags, vests, etc., etc. don't seem to be doing any compensating. The most consistently crazy are the ones with the least safety equipment. Yeah, same here. Actually I think rather than risk compensation, choice bias skews these "studies" as people that use flags and vests etc are already more concerned with safety than the typical users. |
#163
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visibility of DRL
On Tue, 9 Apr 2019 06:39:46 -0700, sms
wrote: If all the riders had somehow been forced to take the same risks, the conclusion would have been different, with the riders using DRLs having even fewer incidents. I call to your attention (again) the data tweaking and fudging that was apparently done to produce a result in favor of riders with DRLs. See my cursory and superficial analysis at: https://groups.google.com/d/msg/rec.bicycles.tech/CVAE2CuCHo8/VRIyIZ-cAgAJ If you accept my suspicions, the actual results of the study, ignoring a 28% fudging of the treatment group data, would be a 9% INCREASE in accidents by the treatment group over the control group. So far, nobody has commented on this problem and I could use a sanity check to make sure I haven't screwed up somewhere. If someone gave you a DRL to use on your bicycle in trade for filling out a web form with your experiences, would you be: [ ] More [ ] Equally [ ] Less inclined to provide the data compared to filling out the same web form if you were given nothing? It would be interesting to know if the control group, that had NOT been provided with lights, were given free lights at the end of the study. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#164
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visibility of DRL
On Tuesday, April 9, 2019 at 4:15:19 PM UTC+1, Jeff Liebermann wrote:
I call to your attention (again) the data tweaking and fudging that was apparently done to produce a result in favor of riders with DRLs. See my cursory and superficial analysis at: https://groups.google.com/d/msg/rec.bicycles.tech/CVAE2CuCHo8/VRIyIZ-cAgAJ If you accept my suspicions, the actual results of the study, ignoring a 28% fudging of the treatment group data, would be a 9% INCREASE in accidents by the treatment group over the control group. So far, nobody has commented on this problem and I could use a sanity check to make sure I haven't screwed up somewhere. Seems about right to me. But I don't know why you're surprised. Peer review has been a sham for a long time. For instance, if twenty-some years ago the reviewers of Michael Mann's first two "hockey stick" articles were not his students, who basically passed the article as good without asking for either the underlying data or an account of the adjustments made, the world would never have wasted trillions on the myth of global warming, which has since become a touchy-feely religion much in evidence among the more sanctimonious class of cyclists, and others of course: I enjoyed those kids abusing Senator Diane Feinstein about it... Ande Jute Wide awake |
#165
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visibility of DRL
On Tue, 9 Apr 2019 06:39:46 -0700, sms
wrote: On 4/8/2019 6:19 PM, Jeff Liebermann wrote: The problem with DRL is that anyone can see that the light is flashing or not flashing. Everyone in the test group knows that they have a functional device and everyone in the control group knows that they don't have anything to test. Expected results soon turn into actual results. In other words, there's no way I could arrange a double blind study for DRL safety and the results will tend to favor the expected results. Another issue is that the group with the DRLs will be taking more risks. It's called " “risk compensation." In the Odense study, the results would have been skewed by risk compensation. If all the riders had somehow been forced to take the same risks, the conclusion would have been different, with the riders using DRLs having even fewer incidents. The Odense study showed that solo accidents were also reduced by the lights. Which does tend to make one think that simply participating in the study as a part of the "lighted fraternity" had a tendency to make one a bit more careful. -- cheers, John B. |
#166
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visibility of DRL
On 4/9/2019 10:12 AM, jbeattie wrote:
On Tuesday, April 9, 2019 at 6:39:51 AM UTC-7, sms wrote: Another issue is that the group with the DRLs will be taking more risks. It's called " “risk compensation." In the Odense study, the results would have been skewed by risk compensation. If all the riders had somehow been forced to take the same risks, the conclusion would have been different, with the riders using DRLs having even fewer incidents. Yes, I turn on my front flasher and say "f*** that, I'm going for it!" Then I start racing down the middle of the road, going the wrong way -- "I'm king of the world!" And with my helmet, it's no holds barred! Here's a possible mechanism for risk compensation with DRLs: An edge-riding cyclist coasting northward down a hill sees a car either driving south with its left turn signal on, or a car rushing to a stop sign from the east. The rider thinks "It's OK, they'll see my DRL" and doesn't bother to pay attention, keep his hands on the brakes, watch for a potential escape route, keep pedaling* etc. The car crosses his path, and he's not ready for it. (*I do keep pedaling in those situations, even if I'm spinning the cranks against zero resistance. It's a way of telegraphing that I'm not planning on stopping, and the motion may enhance conspicuity. Is that partly why I don't get people pulling out in front of me? I can't say.) The safety mavens around here with their five flashers and three headlights, flags, vests, etc., etc. don't seem to be doing any compensating. The most consistently crazy are the ones with the least safety equipment. I agree that those Scharf imitators probably don't consciously take extra risks. But I do think most of them are edge riders who lose some of their conspicuity due to bad lane position. And since I tend to believe data: Two pieces of data that are not usually gathered after bike crashes, but really should be, are 1) details on the use (or absence) of lights and reflectors, and 2) details on lane position. One colleague of mine tried hard to lobby for better collection of that data in the latest revision of accident reporting forms. She wasn't able to succeed. -- - Frank Krygowski |
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