4 ms·

There's this Ian Walker study: https://www.sciencedirect.com/science/article/abs/pii/S0001457506001540 https://www.sciencedirect.com/science/article/abs/pii/S00

There's this Ian Walker study: https://www.sciencedirect.com/science/article/abs/pii/S0001457506001540 https://www.sciencedirect.com/science/article/abs/pii/S00014... It's a small sample size, so take with a pinch of salt.

threeseed 4y ago
Refutation of the Walker study which "assesses the extent to which the sample size in the original analysis may have contributed to spurious results". https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783373/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783373/
- ndsipa_pomu 4y ago
  Response to the refutation: https://researchportal.bath.ac.uk/en/publications/bicycle-helmet-wearing-is-associated-with-closer-overtaking-by-dr https://researchportal.bath.ac.uk/en/publications/bicycle-he... Olivier and Walter re-analysed the same data in 2013 and claimed helmet wearing was not associated with close vehicle passing. Here we show how Olivier and Walter’s analysis addressed a subtly, but importantly, different question than Walker’s. Their conclusion was based on omitting information about variability in driver behaviour and instead dividing overtakes into two binary categories of ‘close’ and ‘not close’; we demonstrate that they did not justify or address the implications of this choice, did not have sufficient statistical power for their approach, and moreover show that slightly adjusting their definition of ‘close’ would reverse their conclusions. We then present a new analysis of the original dataset, measuring directly the extent to which drivers changed their behaviour in response to helmet wearing. This analysis confirms that drivers did, overall, get closer when the rider wore a helmet.
  - deleted 4y ago
    [deleted]
alan99999 4y ago
What Ian Walker's study failed to do was measure the amount of traffic, let alone the oncoming traffic. As he did different parts of his data collection on different days and on different roads, this key measure which often affects how far a car is able to move out going past a cyclist is a very obvious parameter to take into account. Ian's data set has times of passes in it so it might be possible to crate a proxy for traffic density but I haven't attempted this. I think it's more valid to conclude this study has no credence than to draw any conclusion from it.

threeseed 4y ago

Refutation of the Walker study which "assesses the extent to which the sample size in the original analysis may have contributed to spurious results". https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783373/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783373/

ndsipa_pomu 4y ago
Response to the refutation: https://researchportal.bath.ac.uk/en/publications/bicycle-helmet-wearing-is-associated-with-closer-overtaking-by-dr https://researchportal.bath.ac.uk/en/publications/bicycle-he... Olivier and Walter re-analysed the same data in 2013 and claimed helmet wearing was not associated with close vehicle passing. Here we show how Olivier and Walter’s analysis addressed a subtly, but importantly, different question than Walker’s. Their conclusion was based on omitting information about variability in driver behaviour and instead dividing overtakes into two binary categories of ‘close’ and ‘not close’; we demonstrate that they did not justify or address the implications of this choice, did not have sufficient statistical power for their approach, and moreover show that slightly adjusting their definition of ‘close’ would reverse their conclusions. We then present a new analysis of the original dataset, measuring directly the extent to which drivers changed their behaviour in response to helmet wearing. This analysis confirms that drivers did, overall, get closer when the rider wore a helmet.
- deleted 4y ago
  [deleted]

alan99999 4y ago

What Ian Walker's study failed to do was measure the amount of traffic, let alone the oncoming traffic. As he did different parts of his data collection on different days and on different roads, this key measure which often affects how far a car is able to move out going past a cyclist is a very obvious parameter to take into account. Ian's data set has times of passes in it so it might be possible to crate a proxy for traffic density but I haven't attempted this. I think it's more valid to conclude this study has no credence than to draw any conclusion from it.