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RCHaynes

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Posts: 4
Reply with quote  #1 
As an avid motorcyclist I am always searching for more data and better representations so that I can explain why the mantra 'All The Gear All The Time' is a wise approach.
And now we get this posted by a member: http://www.rideamoto.com//uploads/images/0000/0802/MOTO-DANGERS-R2.png?1257663823 published by the NHTSA.
The poster has determined from this that 3-6 pm is the most dangerous time to ride, and that a helmet is only useful a bit over 1/2 of the time.

So I thought I'd put this up so that folks could shred the design flaws.
PaulM

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Posts: 10
Reply with quote  #2 
While not entirely qualified to comment on the efficacy of the charts, I can comment on the data being presented.

  1. Nobody understands casualties/miles, even if people did, without including numbers of motorcycles on the road it becomes a meaningless stat. Does this mean that in 2007 1.5 people died for every 100million miles for all motorcycles, or only motorcycles in the accidents?
  2. The graph on helmet usage shows only that at least 63% of those involved were wearing helmets. It does not indicate how much the helmet helped. It also took me a moment to realize that the helmet is actually a pie chart! I can barely make out the difference in the colors. Orange, orange and orange?
  3. The area of the collision is interesting, but I'm not entirely sure how much work people can do with this data. It tells me that motorcyclists tend to make more right turns than left. With my experience with the data the police reports, I'm also somewhat skeptical on it's accuracy. The police have hard enough times marking the location (KM on nonurban roads), let alone asking them to analyze the vehicle to determine the area of impact. It's also somewhat confusing, 387 non-collision crashes?  
  4. The hours of the day can be misleading. I'd prefer a granularity of at least hourly. Due to the tilt of the planet, it's also better to reference the part of the day. Morning, noon, evening, night. 6 PM could be dark in the winter and daylight in the summer. 
  5. The weekend/weekday graphs also seem to be misleading. Does it really mean to imply that the total number of injured in the weekend between 6-9 is only 100 less than the total number of injured on weekdays between 3-6? I'd expect the number to be around 40% of the weekday. And are those the total numbers for the year? It's hard to tell if it equals the 5000 according to the Fatalities by Vehicle Type.
  6. On top of the stacked area graph being only useful for showing the 20-29 group and total number of people injured, it's not sorted correctly. The <20 is between the 40-49 and 50-59.
  7. The graphs seem to have a problem deciding whether to report on 2007 or 2008! The Motorcyclists Injured by Age, Fatalities Rate by Miles Driven, Motorcyclists Injured by Helmet Usage and the percent of  motorcyclists/total injured all go to 2007, while the remaining graphs go to 2008. Are the 60% daytime and 9% alcohol related in 2007 or 2008?
As for your original search, this is something that I threw together about a earlier this year. It's from 2002-2008, and only details on those injured in accidents and whose data is not unknown (roughly 2% of reported involved have unknown safety method usage), and not inapplicable (pedestrians). When I return to work I can rerun the query slicing on motorcyclists only. The Helmet Worn includes motorcyclists and bicyclists.


Safety Methods Involved Fatalities Percentage of Fatalities per Involved Heavily Injured Percentage of Heavily Injured per Involved Lightly Injured Percentage of Lightly Injured per Involved
Helmet Worn 17277 254 1.47% 1855 10.74% 15168 87.79%
Buckled seatbelt 168666 1102 0.65% 6436 3.82% 161128 95.53%
Did not use any safety measures 15790407 2.58% 1311 8.30% 14072 89.12%
Summary 201733 1763 0.87% 9602 4.76% 190368 94.37%

Admittedly there are some problems with this chart, but I believe it proves the point.
grasshopper

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Posts: 247
Reply with quote  #3 
That helmet-shaped pie chart is quite possibly the worst pie chart I've seen!

I'm attaching the png, just in case the link goes away sometime in the future.


Attached Images
Name: MOTO-DANGERS-R2.png, Views: 1464, Size: 146.69 KB


grasshopper

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Posts: 247
Reply with quote  #4 
Per picking apart the the graphs...

Pie Chart: I would rather see 2 charts - 1 for helmeted crashes, and 1 for non-helmeted crashes ... showing the % of riders injured -vs- not injured.  I suspect that such a comparison would show that non-helmeted riders were injured much more often than helmeted riders.

There are 3 area charts showing a time-line, but they do not have consistent time-axes, so it is not easy to compare them.  I would make the time-axes the same, and line them up for easy comparison.  Also, I think they need another chart showing the number of motorcyclists per year (it would be interesting to see that the number of riders has gone up the last few years, while the rate of fatalities and injuries has gone down).

Also, since the jpg file name contains the word 'MOTO', and the numeric format uses spaces instead of commas, I assume this is some European country(?)  It would be good for the graph to specify what country(s) the data is from.

Fralix85

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Posts: 1
Reply with quote  #5 
Though it’s quite an old thread but I was looking for such 2 different pie charts for crashes and both with as well as without helmets. However, couldn’t find any. My uncle who works for a DUI attorney Los Angeles tried too without much success.
sfew

Moderator
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Posts: 845
Reply with quote  #6 
Fralix85,

The fact that you can't find an example of this is a good thing. It would be an ineffective way to display this information. If you're like help in displaying this information effectively, please provide the data and describe what you're trying to communicate with it.

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Stephen Few
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