Have London's roads become more dangerous for cyclists? Statistical study says something has changed on London’s roads

It's all pretty simple. Cycling in London has increased and there are more cyclists amongst more dense traffic than anywhere else!

I really think that denying the obvious is not serving anyone!

'Have London's roads got more dangerous?' Well, apart from pot holes,
how? So the increase in cycling since 2012 has nothing to do with it?

The study is more complex than the report, as any listener to the great More or Less will have heard (http://downloads.bbc.co.uk/podcasts/radio4/moreorless/moreorless_2014010...) because you need to consider not just the consecutive 14 day periods but the non-consecutive ones in order to address whether these deaths were statistically significant. The conclusion: there isn't any significant increase, allowing for increased cycling in London, and that cycling remains life lengthening rather than reducing.

Of course, if we allow drivers to add Google Glass to their armoury ...

A 5% chance is two standard deviations away from the mean occurrence and tends to be the point where data becomes "statistically significant" and 2.5% even more so (can't remember my bell curve analysis off the top of my head). Bottom line, it was very unusual and even more so if you narrow it by vehicle type involved.
What really irks me is that it is beyond obvious if you observe certain driving behaviours as alluded to above and it could be vastly improved at a pen stroke - change the terms for tipper tricks to day rates and not per load (most of them are crossrail which is a government contract). Insisting on cycle training for all the drivers before they can enter the low emissions zone might not be a bad idea as well.

Actually just read the article on which this is based and the reporting here is very misleading.

They actually conclude that cycling in London is safe and that the likelyhood of dying is quite small.

They themselves seem to say that while the events of November are significant they cannot say why and that more analysis is due. Which is pretty much what some said at the time.

Typically with statistics it isn't really saying anything except that November was an unusual month. A very high mortality rate for
Cyclists, without saying why....and that is the crucial point.

I went to the casino the other day. I was betting on roulette. Whenever I put higher stakes bets on they won more than my low stakes bets (I made random and arbitrary bets). Statistically using the model above the high stakes bets look significant, but if you put it over the course of all my roulette bets then it looks like the significance of the bets is more reduced. Statistics can exceed in applying meaning to meaninglessness. In fact that is the problem with statistics, it is applied frequently to give meaning to events which have none. And even once it has done so there are arguments about the truth in the meaning. I'm sure mathematically the results are fine, but I would guess that the sample size the statisticians were working with and breath of data was too small to add any real quality of meaning. In fact their conclusion is 'significantly' vague.....quo bono?

More details on the statistical methods used are available here:

http://understandinguncertainty.org/when-cluster-real-cluster

I'm not sure why some commentators are railing against the findings, but I think that Professor Speigelhalter is adequately qualified to make the statements that he does - more so than the armchair statisticians that appear to have popped up.

I think this must be a commentary on the misuse of statistical significance rather than on road safety for cyclists. Taking an exceptional event and then testing it for significance is simply wrong. I can't believe that an RSS publication would say that this was "a sign of increased danger on the capital’s roads".

Baffling.

Not even wrong. Although the question "Should you forsake two wheels for four, or more, in order to preserve life and limb?" does imply some dubious assumptions which would tend to indicate they're well on the way.

Saying something is statistically significant is of no use other than a bald, lonely statement of statistical likelihood. It says nothing about correlation with or causality from other factors - weather, time of accident, physical infrastructure, legal & criminal justice environment, rider training & behaviour, driver training & behaviour, changes from BST to GMT, and so on. There's a capital letter at the start of this sentence, but it says bugger all about grammatical structure of language other than that I start sentences with a capital letter. Less headline grabbing, more analysis plz.

I did a quick poisson analysis a while ago, 6 deaths is indeed unlikely due to chance (as the article says, you expect clumpiness - if you had an average of one death a month, it would very rare to experience a year where exactly once cyclist died each month).

The paper seems, however, to assume death rate is constant throughout the year (can't tell this for sure, don't you just love academic paywallls? -but that's a rant for elsewhere). That seems a dodgy assumption - I'd be explicitly looking for a consistent spike just after the clocks have changed, for example - and the fact that overall deaths this year were within normal variance suggests this is not exceptional at all unless the rest of the year was exceptionally safe.

It was coincidence, probably in addition to a seasonal spike.

Break it down by vehicle type involved in KSI's and you will find a disproportionate statistical outlier.

Published Nov13.

Add to this chart a line showing the increase in the number of cyclists on London roads and you'll find the answer to the question posed in the headline is "No".

I am glad they have undertaken such an in depth analysis. Anecdotally there is a particular type of vehicle involved driven in a particular fashion that is disproportionately responsible for the deaths and yes I am pointing the finger at tipper trucks driven by impatient, inconsiderate time focused drivers. Deal with this category and you will significantly alter the statistical outcome.
Sure there is an element of cyclist training (not going up the left side of lorries) but this will require a total overhaul of infrastructure design which predominantly sends you up the left side of all traffic at junctions so the novice naturally assumes this is what should be done.
What is upsetting is that politically no one feels responsible enough to take simple obvious actions to prevent further needless loss of life on our roads.

Never in the field of human commuting has so much been said to say so little.