:Cyclostat

We, the biking community, are associated with reduced motor vehicle fatalities.

Attractive and Convincing Graph:

Boring Technical Note: This attractive and convincing graph is an approximation of a partial regression. Since it’s damned difficult to graph 2 variables while controlling for a third, I just decided to divide both variables by the third variable (Mmiles). With the partial regression, you actually get an intercept of .832, but since my third variable is not 0, we can’t use that -so I approximated one that looked good. The actual stepwise regression formula is y=.832+1.68x-.012y, where x=millions of miles, and y=numbers of cyclists.

Simple version: More bikers = Less Motor Vehicle Fatalities.

Complicated Stuff:

A partial negative correlation was found between the number of motor vehicle accidents and the number of workers who report cycling to work. This is basically a correlation between my previous post and the post about motor vehicle fatalities. The correlation was significant, using a partial correlation that controlled for 100 milion miles driven per state, r(354)=-.438, p<.001.

This basically means that an increase in cyclists is associated with having fewer motor vehicle accidents, after controlling for the number of miles driven.

It is important to point out that this r value is compiled of every state data for years 2001 to 2007. So, Massachusetts would have 7 data points for bike stats, correlated with 7 points for fatalities. If the years are treated independently, each correlation is also significant to at least p<.02, with an r no greater than -0.32 and no less than -0.52.

Caveats!

Correlation is not causality. But there is a definitely an inverse association between the number of bikers commuting to work and the number of motor vehicle fatalities.

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