You are reading a single comment by @gbj_tester and its replies. Click here to read the full conversation.
  • Situation is as follows:

    Chap A is making an assertion that the apparent effect of speed cameras to reduce accident rates and serverity of outcome is actually regression to the mean, rather than anything to do with people having to drive more slowly.

    As far as I understand RTM this relies on the camera having been sited at a spot that had just experienced a spike in accidents - and the reduction observed after the camera install is due to the number of accidents trending down to the mean.

    What I'm failing to see is how this could be used to explain a reduction in accidents at an accident blackspot post camera install - as the mean (if I am using the terms correctly) has been well above average accident rates for the UK for some time, hence it being known as an accident blackspot.

    What am I missing?

  • What am I missing?

    That a fairly short duration random spike in the accident rate can be sufficient to get a place a reputation as a black spot.

About

Avatar for gbj_tester @gbj_tester started