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#1361
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On Sun, 6 Feb 2005 23:33:43 -0500, "Riley Geary"
wrote: Once again, you seem to be confusing an apparent safety benefit, resulting most likely from selective recruitment of helmet users among Florida's bicyclists, with the real thing--which remains to be determined, but is almost certainly much less than 40%. In the UK 25% of all cyclist fatalities are due to being crushed to death by turning goods vehicles, most of them in London. If you believe our helmet promotion charity that means that helmets would prevent in excess of 100% of the balance :-) Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at CHS, Puget Sound |
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#1362
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Can I get a cite on the Utah study ? It looks interesting
John Kane Kingston ON |
#1363
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Riley Geary wrote:
bicyclists, then we not only have a reasonably coherent explanation as to why bike helmet use has had little or no favorable impact on overall bicycle fatality rates, but a powerful argument against imposing a MHL on bicyclists as well. It's a very weak argument, non-existent actually. Look at the Louisiana data. From 1997 to 2000, helmet use went from 100% to 52%, and motorcyclists killed per 10,000 registrations went from 3.2 to 7.9. So helmet use fell by a little less than 50%, and fatalities went up by 140%. What this says is that the people that would have benefited the most from wearing a helmet, were the ones that chose not to wear one. Not that this is surprising. I don't think that this is the data you want to use in any argument againt bicycle helmet laws! The Florida data on bicycle helmet versus non-helmeted riders showed a much smaller difference in fatality rates. |
#1364
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On Sun, 06 Feb 2005 16:55:16 GMT, "Steven M. Scharf"
wrote in message . net: Every study suffers from the possibility of self-selection. And some are more honest about it than others. Compare Spaite: "A striking finding was noted when the group of patients without major head injuries (246) was analyzed separately. Helmet users in this group still had a much lower mean ISS (3.6 vs. 12.9, p less than 0.001) and were much less likely to have an ISS greater than 15 (4.4% vs. 32.1%, p less than 0.0001) than were nonusers. In this group, 42 of 47 patients with an ISS greater than 15 (89.4%) were not wearing helmets. We conclude that helmet nonuse is strongly associated with severe injuries in this study population. This is true even when the patients without major head injuries are analyzed as a group; a finding to our knowledge not previously described." with the 1989 Seattle study, which compares radically different populations of cyclists, assumes an atypical and homogeneous group to be typical in terms of helmet wearing rate (despite co-author Rivara's own contemporaneous street counts proving otherwise), and attributes all the difference to the helmets themselves, a classic confusion of cause and effect. Guess which one is quoted by every single helmet promotion campaign? Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 85% of helmet statistics are made up, 69% of them at CHS, Puget Sound |
#1365
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On Mon, 07 Feb 2005 17:57:14 GMT, "Steven M. Scharf"
wrote in message . net: bicyclists, then we not only have a reasonably coherent explanation as to why bike helmet use has had little or no favorable impact on overall bicycle fatality rates, but a powerful argument against imposing a MHL on bicyclists as well. It's a very weak argument, non-existent actually. "The results indicate that risk compensation may modify the effectiveness of PE [protective equipment, sic.] for children engaged in sports and leisure activities. Conversely, the findings also suggest that those wearing PE may be a cautious subgroup." - Risk compensation in children?s activities: A pilot study, Mok D, Gore G, Hagel B, Mok E, Magdalinos H, Pless B. 2004. Paediatr Child Health: Vol 9 No 5 May/June 2004. Interestingly Pless set out to prove exactly your assertion, and ended up concluding that risk compensation does apply to cycle helemts specifically, as it seems to for most other forms of human activity (well documented by Wilde and Adams). So, where is your actual evidence for discounting risk compensation? Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 85% of helmet statistics are made up, 69% of them at CHS, Puget Sound |
#1366
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#1367
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"Steven M. Scharf" wrote in message ink.net... Riley Geary wrote: this is mostly because increases in motorcycle registrations in those same states have also outpaced the average rate of increase in other states. This is not true. The fatalities have _far_ outpaced the increase in registrations. Motorcyclists Killed per 10,000 Registered have steadily increased since the repeal of the law. You can see the data at: "http://www.nhtsa.dot.gov/people/injury/pedbimot/motorcycle/kentuky-la03/Law ChgLa.html" NHTSA has put out a fair number of pretty shoddy research reports over the years, but you've managed to latch onto the worst part of one of their lamer efforts, "Evaluation of the Repeal of Motorcycle Helmet Laws in Kentucky and Louisiana, DOT HS 809 530, October, 2003." It's interesting that you didn't direct our attention toward section IV dealing with Kentucky, but instead chose section V dealing only with Louisiana. At least the section dealing with Kentucky has some reasonable looking helmet use/injury data and motorcycle registration numbers, though it should be obvious from Table 5 (75-77% of all injured motorcyclists prior to 1998 were listed as using helmets) that the observed helmet use survey data presented in Table 2 can't possibly be accurate, particularly prior to the 1998 repeal of Kentucky's MHL (96% helmet use rate among motorcyclists). But apparently the conclusion that "Motorcyclists killed per 10,000 registered motorcycles increased from less than 7 under the universal helmet law to more than 8 following repeal" didn't sound dramatic enough, so you went with the section on Louisiana instead. Unfortunately, the data presented in section V dealing with Louisiana appears to be largely bogus. Table 7 on observed helmet use survey data, purporting to show that essentially 100% of motorcyclists prior to the 1999 repeal of Louisiana's were using helmets, is almost certainly a fabrication since data in table 3 of the report "An Analysis of Motorcycle Crashes 1996 to 2002" published by the Louisiana Highway Safety Commission http://lhsc.lsu.edu/SpecializedRepor...d_5-1-03_2.pdf indicates just 58% of all injured motorcyclists were actually using helmets prior to 1999, which rate has only declined to 48% post-1999. Likewise, the registration data in Table 10, supposedly from the Louisiana Dept of Public Safety, bears no relationship at all to the same data reported via the FHWA and BTS, and presented by NHTSA itself through its annual Traffic Safety Fact Sheets dealing with Motorcycles: http://www-nrd.nhtsa.dot.gov/departm.../AvailInf.html Year Reg MC Fatalities/10,000 Reg MC (LA-DPS) 1997 60042 3.2 1998 57189 5.9 1999 64075 6.2 2000 72445 7.9 Year Reg MC Fatalities/10,000 Reg MC (NCSA) 1993 38000 7.6 1994 36000 7.8 1995 36000 7.8 1996 36000 7.8 1997 37000 5.4 1998 37000 9.5 1999 39000 9.7 2000 43000 9.3 2001 48000 11.8 2002 51000 12.9 2003 54000 12.6 The other problem here is that the LA-DPS data conveniently begins with 1997, a year with an anomalously low number of motorcycle fatalities in Louisiana. Was this simply an innocent choice of both the data range and data source by the author of section V, or was it deliberately chosen to mischaracterize the increase in motorcycle fatalities per 10,000 registered motorcycles as being much higher than it really was following repeal of Louisiana's MHL? Look, most of us here are opposed to MHLs for both motorcycles and bicycles, but this is in spite of the data, because of the personal freedom aspect. It does this cause no good to lie about reality. And who exactly is doing the lieing about reality here? Riley Geary |
#1368
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"Steven M. Scharf" wrote in message ink.net... Riley Geary wrote: bicyclists, then we not only have a reasonably coherent explanation as to why bike helmet use has had little or no favorable impact on overall bicycle fatality rates, but a powerful argument against imposing a MHL on bicyclists as well. It's a very weak argument, non-existent actually. Really? Then how do you explain the demonstrated fact that in most states with a MHL for which we have reasonably reliable helmet use data on non-fatally injured motorcyclists, helmeted motorcyclists appear to have a much greater chance of ending up in a potentially fatal crash than their non-helmeted counterparts, even though they obviously have a better chance of surviving such a crash once it occurs. Look at the Louisiana data. Yes, let's do that, but with an open mind this time as to the source of that data. From 1997 to 2000, helmet use went from 100% to 52%, and motorcyclists killed per 10,000 registrations went from 3.2 to 7.9. So helmet use fell by a little less than 50%, and fatalities went up by 140%. What this says is that the people that would have benefited the most from wearing a helmet, were the ones that chose not to wear one. Not that this is surprising. See my analysis of this in my previous response to you today. Needless to say, none of this "data" stands up to close scrutiny. OTOH, if you really want to take another look at the Louisiana data, I'll simply point out that from 1994-98, prior to repeal of their MHL, 98 helmeted motorcyclists were killed, but only 42 non-helmeted motorcyclists; while 2537 helmeted motorcyclists survived with non-fatal injuries, and 2109 non-helmeted motorcyclists. This gives us an odds ratio of (98/42)*(2109/2537) = 1.94 -- meaning helmeted motorcyclists in Louisiana were then nearly twice as likely to end up with a fatal injury relative to non-helmet-using motorcyclists. After repeal though, from 2000-03 only 83 helmeted motorcyclists were killed, but 173 non-helmeted motorcyclists died; while 2381 helmeted motorcyclists survived with non-fatal injuries, along with 2637 non-helmeted motorcyclists. This gives us a completely different odds ratio of (83/173)*(2637/2381) = 0.53 -- meaning helmeted motorcyclists are now only half as likely to end up with a fatal injury relative to non-helmet-using motorcyclists. If you can explain this nearly four-fold change in the apparent effectiveness of motorcycle helmets before and after repeal of a MHL without invoking some form of risk compensation, I'ld be very interested in hearing it. After all, I don't necessarily claim any of my analyses to be infallible, let alone the Final Word on the subject, so if you have a reasonable alternative to propose, I'ld be more than willing to consider it. I don't think that this is the data you want to use in any argument againt bicycle helmet laws! I know it's not data you would want to continue treating as either reliable or legitimate now... The Florida data on bicycle helmet versus non-helmeted riders showed a much smaller difference in fatality rates. And still you haven't said a word about the Florida motorcycle helmet data I've commented on at length, and which shows the same sort of effect with respect to repeal of a MHL as noted above for Louisiana. Riley Geary |
#1369
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Riley Geary wrote:
Year Reg MC Fatalities/10,000 Reg MC (NCSA) 1993 38000 7.6 1994 36000 7.8 1995 36000 7.8 1996 36000 7.8 1997 37000 5.4 1998 37000 9.5 1999 39000 9.7 2000 43000 9.3 2001 48000 11.8 2002 51000 12.9 2003 54000 12.6 The other problem here is that the LA-DPS data conveniently begins with 1997, a year with an anomalously low number of motorcycle fatalities in Louisiana. Was this simply an innocent choice of both the data range and data source by the author of section V, or was it deliberately chosen to mischaracterize the increase in motorcycle fatalities per 10,000 registered motorcycles as being much higher than it really was following repeal of Louisiana's MHL? It was both innocent and deliberate. It was the year before the repeal, versus the year of the repeal. Totally logical. But if you want to average 1993-1997, then average 1998-2003, that's fine too. 7.3 per 10K with MHL versus 11.0 per 10K after the repeal. So it's only a 51% increase in fatalities. Sorry Riley. There is just no way you can twist the data to prove what you're trying to prove. And it doesn't matter anyway. The states did the right thing by repealing the MHLs, but don't kid yourself into thinking that they did it without knowing that there'd be consequences in the fatality rates. |
#1370
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b_baka wrote:
I would side with the helmet people a little more if bicycle helmets were more comfortable to wear, and if they were more effective. A little design research might go a long way here. At least in this thread, there are no people that have come out in favor of the coercive mandatory helmet law. So you don't have to side with anyone. It's basically an argument over whether or not helmets have any effect in the reduction of injuries or deaths in bicycle crashes. Mose people recognize that it is possible to oppose mandatory helmet laws, while at the same time recognizing the fact that helmets do have a positive effect when crashes occur. The statistical data to support the latter point is overwhelming and incontravertible (though each study shows different percentages, every study supports the basic premise). There are really only 3-4 people that consistently claim that helmets are worthless, apparently believing that unless they can convince someone of this, that helmet laws will be passed. Most of us believe that helmet laws are a bad idea despite the relatively small benefit in terms of injury and fatality reduction. No one believes the "if it saves one life then it's worth it," line of thinking. |
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