Different helmet data

Discussion in 'UK and Europe' started by Pk, Feb 5, 2004.

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  1. Pk

    Pk Guest

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  2. In article <[email protected]>, "PK" <[email protected]> writes:
    |> Taken to new thread to focus discussion on the DATA and analysis.
    |>
    |> I came across this from a google search (helmet reduction other injuries
    |>
    |> http://depts.washington.edu/hiprc/childinjury/topic/bicycles/index.htm
    |>
    |> http://depts.washington.edu/hiprc/childinjury/topic/bicycles/helmeteffect.htm
    |>
    |> perhaps someone more familiar with all the data can set this in context for me.

    I would have to go back to the original papers again, and have neither the time nor the inclination.
    When I did so before, I was horrified at the systematic distortion of the statistics to support the
    dogma. And I am a fair old cynic, so it takes quite a lot to horrify me.

    Regards, Nick Maclaren.
     
  3. Just Zis Guy

    Just Zis Guy Guest

    "PK" <[email protected]> wrote in message
    news:[email protected]...

    > http://depts.washington.edu/hiprc/childinjury/topic/bicycles/index.htm
    >
    http://depts.washington.edu/hiprc/childinjury/topic/bicycles/helmeteffect.htm

    > perhaps someone more familiar with all the data can set this in context
    for
    > me.

    The context is pretty simple. This is a list of reports and meta-analyses, most of which can be
    traced back to the original series of reports by Thompson, Rivara and Thompson and others. It
    includes the original discredited 88% figure. It includes small case-control studies, and excludes
    whole population and time series data. As usual with such meta-analyses it adds nothing to the body
    of knowledge save the fact that the authors are not prepared to consider the reasons why the claimed
    benefits are never exhibited at the population level.

    And I would be disinclined to characterise this as "different" since I think most of these studies
    have been analysed on <url:http://www.cyclehelmets.org>.

    If you want to understand the weakness of this model, consider the following: analysis of casualty
    data from emergency rooms indicates that Kevlar vests reduce the incidence of knife wounds.
    Therefore Kevlar vests should be compulsory.

    Note the flaws:
    1. The solution is not proportional to the actual risk
    2. The solution does not address the source of risk, only it's after-effects
    3. The solution will not help those whose wounds are on parts of the body not covered by the vests
    4. The solution ignores the possibility that people wearing Kevlar vests will confront knife-
    wielding assailants rather than run, so increasing their level of risk
    5. The solution ignores the possibility that the behaviour of knife-wielding assailants will change
    for the worse
    6. The solution enshrines in law the idea that the source of risk cannot be reduced

    There may be other problems, these are just the ones which occur to me regarding the hospital-
    centred case-control studies on which helmet promotion is predicated.

    The whole helmet compulsion thing is close to being a my-dog-is-a-cat scenario, as per Yes Minister,
    except for the crucial fact that in this case nothing need actually be done - or at least, not at
    the victim level.

    --
    Guy
    ===

    WARNING: may contain traces of irony. Contents may settle after posting.
    http://www.chapmancentral.co.uk
     
  4. > Taken to new thread to focus discussion on the DATA and analysis.
    >
    > I came across this from a google search (helmet reduction other injuries
    >
    > http://depts.washington.edu/hiprc/childinjury/topic/bicycles/index.htm

    Bicycle Injuries Scope of the Problem I like the way it starts off - 67,000,000 cyclists and only
    750 deaths a year - not bad odds!

    > http://depts.washington.edu/hiprc/childinjury/topic/bicycles/helmeteffect.htm
    >
    > perhaps someone more familiar with all the data can set this in context for me.

    The column headed 'Study quality and Conclusions' does not say anything at all about the quality of
    the study. A simple litmus test is to find the flawed Thompson, Rivara, and Thompson study and see
    if they pick up on the hideous errors in it and their own later revision to the 88% figure. The only
    thing written related to the Study Quality is "Population-based control group provides the best
    estimate of helmet effect." Hmmm, not when your study is this flawed![1]

    In the context of the great helmet debate, we have to reconcile the results of all these studies
    with the non-results from places that have tried legislation, or, why do helmets stop working when
    everyone wears one! It should be noted that there are at most only a couple of people on this
    newsgroup that completely deride helmets as useless. Most just rightly point out that they're
    useless when you headbutt cars at speed.

    The other (fairly major) thing is to point out that cycling is still safer than walking, so what's
    the bloody problem in the first place.

    [1] Critiques of this study can be found at http://www.lesberries.co.uk/cycling/helmets/seattle.html
    http://www.cyclehelmets.org/papers/c2006.pdf

    ---
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  5. Gonzalez

    Gonzalez Guest

    On Thu, 5 Feb 2004 10:24:21 +0000 (UTC), "PK"
    <[email protected]> wrote:

    > Taken to new thread to focus discussion on the DATA and analysis.
    >
    >I came across this from a google search (helmet reduction other injuries
    >
    >http://depts.washington.edu/hiprc/childinjury/topic/bicycles/index.htm
    >
    >http://depts.washington.edu/hiprc/childinjury/topic/bicycles/helmeteffect.htm
    >
    >perhaps someone more familiar with all the data can set this in context for me.

    Case studies suggest that you are significantly more likely to escape serious head injuries if you
    wear a helmet, but that wearing a helmet has no significant impact on facial injuries.
     
  6. Just Zis Guy

    Just Zis Guy Guest

    On Thu, 05 Feb 2004 17:56:37 +0000, Gonzalez
    <[email protected]> wrote:

    >Case studies suggest that you are significantly more likely to escape serious head injuries if you
    >wear a helmet,

    Actually they suggest that the groups which wore more helmets was less likely to experience a head
    injury (severity unspecified) when they crashed, than the group which wore fewer helmets. Since the
    correlation between the two groups is often very poor, and the probability of crashing per unit
    exposure is not even considered, this is of academic interest only.

    Guy
    ===
    May contain traces of irony. Contents liable to settle after posting.
    http://chapmancentral.demon.co.uk
     
  7. Just Zis Guy

    Just Zis Guy Guest

    On Thu, 5 Feb 2004 10:24:21 +0000 (UTC), "PK"
    <[email protected]> wrote:

    > Taken to new thread to focus discussion on the DATA and analysis. I came across this from a google
    > search (helmet reduction other injuries
    > http://depts.washington.edu/hiprc/childinjury/topic/bicycles/index.htm
    > http://depts.washington.edu/hiprc/childinjury/topic/bicycles/helmeteffect.htm perhaps someone more
    > familiar with all the data can set this in context for me.

    A bnit more context. From the syllabus of a course at Washington U:

    Thursday, January 25

    Lecture: Rivara

    Topic: Burns

    [...]

    Tuesday, January 30

    Lecturer: Thompson

    Topic: Bicycle injuries and their prevention

    1. Chapter 15 in Injury Control - evaluation of a program

    2. Rivara FP, Thompson DC, Thompson RS, Rogers LW, Alexander B, Felix D, Bergman AB. The Seattle
    children's bicycle helmet campaign: changes in helmet use and head injury admissions. Pediatrics
    1994;93:567-9.

    3. Thompson DC, Rivara FP, Thompson RS. Effectiveness of bicycle helmets in preventing head
    injuries: a case-control study. JAMA 1996;
    4:1968-1973.

    5. Thompson DC, Nunn ME, Thompson RS, Rivara FP. Effectiveness of bicycle safety helmets in
    preventing serious facial injury. JAMA 1996;
    6:1974-1975.

    7. Rivara FP, Thompson DC, Patterson MQ, Thompson RS. Prevention of bicycle-related injuries:
    helmets, education, and legislation. Ann Rev Public Health 1998; 19:293-318.

    Washington U is apparently the world centre of helmet promotion and fountain souurce of the
    "pro" stats.

    Guy
    ===
    May contain traces of irony. Contents liable to settle after posting.
    http://chapmancentral.demon.co.uk
     
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