A question of averages

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ChrisHB Jun 2016 6:24pm, 1 Jun 2016 13,215 posts	0 ChrisHB As I run or walk along our road, my impression is that the typical car I notice is driving at around 50 mph. Obviously what I notice is not a fair representation of the facts. When we moved here, the school just up the road reported that the average speed of cars was about 50 mph. About six months ago, the police set up a speed monitoring device, and they report "An initial assessment of vehicle speeds was conducted on 13th October 2015 between the hours of 1400 -1500 hours. The Mean speed (average) was 32.6mph for vehicles travelling towards Gatton Park Road and 28.2 mph for vehicles towards the A23." Obviously an average conceals all kinds of variations, from learner drivers taking their first foray into third gear (of which there are plenty), people like me who drive at 20 if there's nothing behind, and those who take advantage of an empty road. What is a good way to insist that an "average" has nothing to do with the case, and demand that a proper speed trap be set up to stop the maybe 1 in 10 drivers who race past a school with 1700 children?
.B. Jun 2016 6:27pm, 1 Jun 2016 23,636 posts	0 .B. Is the speed limit 30mph Chris?
ChrisHB Jun 2016 6:33pm, 1 Jun 2016 13,216 posts	0 ChrisHB sorry, yes.
Fragile Do Not Bend Jun 2016 6:45pm, 1 Jun 2016 841 posts	0 Fragile Do Not Bend I don't know, but you could drive faster and push the average up a bit 😄
.B. Jun 2016 6:45pm, 1 Jun 2016 23,639 posts	0 .B. I think if the figures show that on average car drivers (in one direction) are breaking the speed limit then surely something needs to be done - this is outside a school afterall. What would be interesting to know is how many vehicles and what were the speeds that were used to get the average. Surely they must know how many broke the speed limit and by how much. What were the fastest speeds recorded? It only takes one speeding driver to cause a tragedy, I'm not sure that the averages are very helpful, what is important is how many speeding drivers there were and by how much because the faster the speed the more likely to cause death or serious injury. Do you think they would provide more detailed figures?
Fragile Do Not Bend Jun 2016 6:51pm, 1 Jun 2016 842 posts	0 Fragile Do Not Bend I imagine 2-3pm is a relatively quiet time of day, and people are less likely to be in a hurry. The average probably goes up between 8-9am when people are rushing to get to work. One the other hand there's a school which might cause gridlock at that time of day.
ChrisHB Jun 2016 7:03pm, 1 Jun 2016 13,217 posts	0 ChrisHB Quite right, B. I'm looking for a compelling argument that will show any fool that an average has nothing to do with the case.
Winded Jun 2016 10:24pm, 1 Jun 2016 4,175 posts	0 Winded I doubt they issue tickets for 32.8mph in a 30 - 34mph is more likely so if it is a median as well as a mean they might not bother with a trap that would not produce tickets. I thought that it was mostly 20 outside schools now, though it is 30 outside the village school here with added flashing lights for a 20mph part time limit- I have yet to see the lights flash, they may have lost the remote or something.