From: rlewis@muskwa.ucs.ualberta.ca (Robert Lewis)
Subject: Re: Risk ratio (was: Ticketing illegal cycling)
Organization: University Of Alberta, Edmonton Canada
Date: Sat, 7 Nov 1992 05:58:31 GMT


tomk@netcom.com (Thomas H. Kunich) writes:

>In article <rlewis.720943708@muskwa.ucs.ualberta.ca> rlewis@muskwa.ucs.ualberta.ca (Robert Lewis) writes:
>>
>>	The principal problem is the extent to which the under-reporting
>>	of accidents varies with different travel methods, situations,
>>	and severities of injury.  There is much evidence that people do
>>	not always report cycle accidents.

>I wonder if this doesn't mean that there are such slight injuries that
>it doesn't make any sense to report them? 

If Mr. Kunich had included the sentence following those he quoted it
would have been clear why unreported accidents cannot simply be passed
off as 'minor scrapes' (though some might be such).

	The principal problem is the extent to which the under-reporting
	of accidents varies with different travel methods, situations,
	and severities of injury.  There is much evidence that people do
	not always report cycle accidents.  Several studies have
	compared the number reported by the police with the number
	treated in hospital for injuries.  (British Medical Association 
	1992:48) 

As the comparison is of police reports with injuries serious enough to
require a trip to the hospital I think that this is fairly clear.

	A...study showed that 74 per cent of the slight reportable 
	accidents' and 61 per cent of the 'serious reportable accidents' 
	go unreported.  (British Medical Association 1992:48) 

Even assuming that all of the "slight reportable accidents" were "such 
slight injuries that it doesn't make any sense to report them" (i.e.,
they really weren't reportable accidents at all), one is still left with
the 61% of 'serious reportable accidents' which were not reported.

>                                          What is to be gained other
>than having self-proclaimed experts using such figures as "proof" that
>bicycling is unsafe?

The percentage of reported versus unreported accidents says nothing
about the safety of cycling.  The point to the above quote was to
challenge Mr. Robinson's contention that, "In Britain...they include 
all hospital reports of accidents in the official figures", which he was
using to argue against the suggestion that bike-bike collisions were a
significant hazard for cyclists (note NOT 'the only' or 'the main' or
the 'most serious', just 'a significant').  In fact the point that
bicycle accidents are not reported in the same way as motor vehicle
accidents (in particular that they are under-reported except when there
is a fatality) argues against the argument that, while bicycle accidents
are less common than motor vehicle accidents, they are more serious.

>>As the BMA study suggests, and fairly consistant with the North American
>>findings, the accident reports of the police are unreliable as regards
>>cycling accidents.

>Again, you are making the assumption, and a highly unwarranted one at that,
>that these 'accidents' are significant. As a matter of fact, in states
>that require reporting of auto accidents they all have a lower limit
>at which point the accident isn't reported. There are literally
>thousands of accidents every day that aren't reported because they fall
>below the minimum damage to be reportable. 

There is nothing "highly unwarranted" in the assumption that none of these 
accidents were significant.  As far as I can tell all of the accidents
refered to in the BMA book all of the accidents were reportable.  In 
Stutts et al. (1988) all of the accidents are graded by a standard scale
(see Table 1) of injury severity and about 20% of the injuries were 
moderate or greater.  They also indicate that adult cyclists had more 
serious accidents than did child cyclists (see Table 2), so one cannot
dismiss serious accidents as something which happens to 'foolish'
children.  As well they report that 15.5% of emergency room reported 
accidents involved motor vehicles while 6.2% involved another cyclist
whereas none of the police reported bicycle accidents involved another
cyclist (65), again bike-bike accidents cannot simply be written off as
of no significance (which was the point of the whole post). 

TABLE 1.  AIS Injury Severity Scale
     	0 No injury 
     	1 Minor injury (e.g., soft tissue wound, broken tooth,   
       	  finger frature) 
     	2 Moderate injury (e.g., non-dislocated fracture of mandible
       	  or ankle) 
     	3 Serious injury (e.g., open and/or dislocated fracture,   
       	  pneumothorax, or hemothorax) 
     	4 Severe, life threatening injury (e.g., splenic rupture) 
     	5 Critical injury (e.g., intracranial hemorrhage, liver   
       	  rupture) 
     	6 Maximum injury (unsurvivable) 


TABLE 2  Percentage of cases with moderate or worse injury 
	 (AIS 2 or greater)                  (%) 
 
          Sex 
            Male                             22.2 
            Female                           11.7 
          Age 
            0-4                               0.0 
            5-9                              15.7 
            10-14                            20.3 
            15-19                            17.9 
            20-24                            19.1 
            25-29                            22.2 
            30-39                            31.3 
            40+                              43.8 
          Admitted to hospital? 
            Yes                              92.0 
            No                               13.7 
          Motor vehicle involved? 
            Yes                              32.3 
            No                               16.9 
          Reported to police? 
            Yes                              42.3 
            No                               15.7 
          Alcohol or drugs involved? 
            Yes                              33.3 
            No                               18.5 
 
References:

British Medical Association (1992).  Cycling Towards Health and Safety.
	Oxford:  Oxford University.

Stutts, J. C.; J. E. Williamson; and F. C. Sheldon (1988). 
	"Bicycle Accidents:  An Examination of Hospital Emergency
	Room Reports and Comparison with Police Accident Data." 
	Transportation Research Record, no. 1168, pp. 60-71.

_________________________________________________________

Robert M. Lewis
Department of Sociology
University of Alberta
Edmonton, Alberta
Canada