Show Me The Numbers
Confession time - I’m a bit of an anorak. I like playing with numbers to see what they’ll say. I mean, without numbers, what have you got?
In God we trust, but everyone else had better bring data!
So I was quite interested in the CTC’s Safety In Numbers campaign that was launched yesterday. Their glossy PDF summary of the research has some lovely graphics, but seemed to pick & choose on the data, so I went for a dig into the fuller Word document (which was also a PDF - go figure) that was also available.
Anyway, like I said, I’m a bit of an anorak. So I thought it would be fun to have a look at the list of 108 districts in England to see how this relationship between safety and numbers stacked up. Believe me, those long winter evenings just fly past:
So what does this tell us? Well, I’ve plotted the CTC’s data of injury rates from various reports, plotted against the data from the 2001 national census (recorded on the day before Daughter was born, so her commuting mode isn’t in the data). I’ve then got Excel to draw one of those clever trend lines through the data, with some picking and choosing to find the one that fits the data best - in this case a power function, with a correlation coefficient of around 0.7.
OK - this is too much information. It’s like when I started talking about Aldi’s bargain basement bib shorts, but without the pain down there, and we’re not going there again. So just take this from it - the number of people riding for regular type getting about stuff, is a good predictor of how safe it is for people to ride their bikes.
Note that I’m not saying that getting more people on the street on their bikes is necessarily what makes the streets safe for cyclists. It could well be the other way round - make the streets safe, and people will ride, confident that it’s a regular, every day, safe kind of thing to do.
My personal feeling (based on no data whatsoever - D’Oh!) is that it’s a little of both.
But what do you think?