Comment 38410

By kevlahan (registered) | Posted February 23, 2010 at 20:45:18

Arbitrarily splitting the intermediate SES rates between the low and high SES bins is not justified statistically, since it assumes that the rate distribution is symmetric about median income, which it clearly isn't (the rate distribution is clearly strongly skewed to lower SES, which is the whole point of this statistic).

If you really wanted to re-assign the rates from intermediate SES bin to the other bins you would need to take into account this asymetry, which would mean much more than half the rate would be assigned to the lower SES bin, giving much the same result as reported in the paper.

Part of the reason one relies on peer reviewed publications is that statistical analysis (and other knowledge) is non-trivial, and making apparently 'fair' assumptions is often not justified. This is a good example. If you really understand the statistical analysis, or find obvious flaws, that's fine, but not just any re-jigging of the numbers is acceptable.

This reminds me of the member of the Indiana State legislature who tried in 1897 to pass a law defining the value of pi to be 4 since irrational numbers are so difficult to calculate with (actually there were six different values in his bill), but I digress.

I agree that in an ideal world including exposure would make the study stronger, but that would be very hard to measure accurately.

It would have been nice if there HAD been a follow-up study, but this report has just sat on the shelf for the past 10 years. I am frankly appalled that the City did not look at the results and say 'This is shocking, let's try to follow-up and double check the analysis: our preferred road design may be injuring our most vulnerable children at 2.5 times the rate of an alternate design'. Instead, the report was either dismissed out of hand, or ignored.

Of course, there are actually reasons to expect the exposure rate might actually be lower on one-way streets since pedestrians try to avoid walking along busy one-way streets like Main and Cannon if possible (because they feel unsafe and unpleasant).

The City has been advised by experts on walkability, urban design and safety to convert to two-way. There are multiple reasons this is a good idea, safety is just one.

We also have our very own control-study in James N, which was written of by its own councillor Ron Corsini in the early 2000s as having no future commercially. It has experienced a commercial renaissance, and two-way conversion was clearly one of the reasons. It is also not a coincidence that the successful commercial streets in the old City are all two-way (e.g. Concession, Westdale Village, Locke St, Ottawa St).

The frustration comes from the fact that the one-way conversion happened over night 50 years ago with no consultation or 'phase-in', and yet the bar for going back is now being set impossibly high. All over the US smaller and medium size Cities are doing successful two-way conversions (e.g. Minneapolis, where I was in November), so we don't even have to be a pioneer!

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