Motorcycle fatalities in the GB (excluding Wales)

(Sorry Wales, I just haven’t figured a way of sorting out the population histories given the local government reorganizations that went with Devolution)

 

 

These two figures show Lexis diagrams for (a) the number of reported motorcycle fatalities in England and Scotland between 1985 and the end of 2014 and (b) the per capita fatality rate.   The x axis denotes the year and the y axis denotes the age of the casualty.   The shade of red denotes the number of fatalities (left) or the fatality rate (right).

It seems to be that motorcycle deaths were high amongst young riders in the mid-1980s.   Compulsory Basic Training was made compulsory in both jurisdictions on 1st December 1990.   Fatalities have fallen amongst young adults since then, and it is possible/likely that this is due to the CBT stopping people using a motorbike at all as well as any safety benefits of only allowing youngsters on the road with this minimal training package.

Another strong feature of the data is that deaths seem to have fallen noticeably in the 2010s.   It’s maybe striking that there have been drops in the numbers of registered motorcycles coinciding with the recession which started just before then.

 

The most interesting thing about these Lexis diagrams is that it is possible to follow Cohorts.   The dotted black lines depict the 1955, 1961, 1967, 1973 and 1979 cohorts respectively.    It is therefore possible to see for example that the middle line (the 1967 cohort) recorded the highest number of fatalities around 1986.   But following the middle line it is possible to claim that as this cohort ages the death count/rate fell dramatically until they were about 25.   But as you continue to follow the cohort, the death count/rate remains roughly constant until about 2010 (when this cohort were 43).   It does appear possible to make the same claim of other cohorts.   After an initial rapid decline in fatalities / the death rate, the numbers / rate remain constant until around 2010.    The reason this is so interesting is because there was a strong narrative in the 2000s of the “Born Again Biker”, people who had ridden when they were younger but took up riding again in their middle ages.   It would be unwise to read too much into these data, but they don’t sit comfortably with that interpretation.   It looks more as if we have some very strong cohort effects.   Biking was very popular among the 1967 cohort.   By the 2000s a lot of bikers on the road (a high proportion given that CBT seems to have deterred youngsters from riding) were from that cohort.   So the large number of middle aged motorcycle casualties in the 2000s could be due to the relative numerical importance of this cohort more than it was due to the “Born Again Biker” phenomena.

If this were just a narrative about interpreting / over interpreting data from some simple visuals it would be slightly interesting.   But the point seems to be that the competing interpretations suggest very different interventions to reduce motorcycle injury.

 

 

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