M4 Camera muppets claiming success...
M4 Camera muppets claiming success...
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mechsympathy

Original Poster:

58,854 posts

286 months

Thursday 9th August 2007
quotequote all
Again: A bit from the local news Apparently 45% drop in KSIs. Oddly enough noone is pointing out that they claimed 54% last year....

Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
mechsympathy said:
Again: A bit from the local news Apparently 45% drop in KSIs. Oddly enough noone is pointing out that they claimed 54% last year....
So are you saying:

1) that there has been no change in KSI.
OR
2) there was a change, but it has nothing to do with cameras.
OR
3) the figures 54% last year to 45% overall are incorrrect.
OR
4) the figures 54% last year to 45% overall are correct but you don't understand how that can be.

BFF

Edited by Big Fat F'r on Thursday 9th August 12:19

mechsympathy

Original Poster:

58,854 posts

286 months

Thursday 9th August 2007
quotequote all
I'm saying I agree with Paul from Safespeed here: http://news.bbc.co.uk/1/hi/england/wiltshire/49056...

Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
mechsympathy said:
I'm saying I agree with Paul from Safespeed here: http://news.bbc.co.uk/1/hi/england/wiltshire/49056...
Ah right (yes, he has a good point about needing data).

The bit that gets me is where it says "Figures suggest that since then, there has been a 57.89% cut in the number of people killed or seriously injured".

Well, the figures may suggest various things, but since the figure is the measured reduction, then it doesn't suggest it, it simply records it. What is up for debate is the cause, not the effect.

I'm wondering how long it will take for Paul to raise RTTM.

BFF


Edited by Big Fat F'r on Thursday 9th August 12:38

smeggy

3,241 posts

270 months

Thursday 9th August 2007
quotequote all
Big Fat F'r said:
So are you saying:

1) that there has been no change in KSI.
OR
2) there was a change, but it has nothing to do with cameras.
OR
3) the figures 54% last year to 45% overall are incorrrect.
OR
4) the figures 54% last year to 45% overall are correct but you don't understand how that can be.
Some of 1, 2 and 3. There probably wasn't a change in overall KSI. Any reduction of KSIs at camera sites are likely nothing to do with the cameras.

said:
At specifically signed camera sites on the M4, fatal and serious injury casualties were down 49 per cent, with all injuries down 54 per cent.
westerndailypress

readitwww.safespeed.org.uk/rttm.html


Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
smeggy said:
Big Fat F'r said:
So are you saying:

1) that there has been no change in KSI.
OR
2) there was a change, but it has nothing to do with cameras.
OR
3) the figures 54% last year to 45% overall are incorrrect.
OR
4) the figures 54% last year to 45% overall are correct but you don't understand how that can be.
Some of 1, 2 and 3. There probably wasn't a change in overall KSI. .
Isn’t that just measurable? Either there was a reduction, or there wasn’t.

smeggy said:
Any reduction of KSIs at camera sites are likely nothing to do with the cameras.
Yes, without full data, its true that either the cameras had no effect, or the cameras had full effect.

smeggy]At specifically signed camera sites on the M4[/b said:
, fatal and serious injury casualties were down 49 per cent, with all injuries down 54 per cent.
Doesn’t this show that there was a reduction?

smeggy said:
Oh the unadulterated joy of regression to the mean.

BFF

MilnerR

8,273 posts

289 months

Thursday 9th August 2007
quotequote all
Big Fat F'r said:
smeggy said:
Oh the unadulterated joy of regression to the mean.

BFF
Speaking professionally, regression to the mean is an important factor when claiming anything about effects of a particular variable. Especially when the numbers and time points used are as limited as this. Could you please explain your apparent problem with regression to the mean?

Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
MilnerR said:
Big Fat F'r said:
smeggy said:
Oh the unadulterated joy of regression to the mean.

BFF
Speaking professionally, regression to the mean is an important factor when claiming anything about effects of a particular variable. Especially when the numbers and time points used are as limited as this. Could you please explain your apparent problem with regression to the mean?
Speaking professionally, I have absolutely no problem with regression to the mean. I understand it, and take account of it, in various tasks.

I do however have a problem with anyone who uses RTTM to dismiss all changes on any process. That is not directed at anyone in particular, just those that shout “have you not heard of RTTM” whenever we talk about cameras, as if it somehow magically explains away any change as down to chance.

As I said, we need more data to prove, or disprove, many of the things claimed on here – by both sides.

BFF

alphadog

2,049 posts

264 months

Thursday 9th August 2007
quotequote all
There's all sorts of unknowns in operation here - weather, conditions, suicides off bridges, wheels coming off trucks - the latter 2 incidents contributed to the stats that justified the cameras. How many of these sorts of incidents have happened this year?

I find that I have to put up with more 'encounters' with other drivers who do not check their mirrors before changing lane, follow too close, and box me in by pootling along in the adjacent lanes at the same speed when all the cars are moving at 70 because they are too scared to exceed.

Conversely I encounter fewer problems when it is possible to drive at what feels a better speed for the road - easier to maximise space from other vehicles for longer.

When the motorway's busy it's a different story altogether as it's difficult to reach the speed limit let alone exceed but don't often see the scammers out then.

Edited by alphadog on Thursday 9th August 13:53

MilnerR

8,273 posts

289 months

Thursday 9th August 2007
quotequote all
Just making sure that you weren't guilty of not giving weight to a very important factor when comparing such small data sets. Although I agree that shouting rttm at every stat is not helpful.

We do need more data, but it has to be data collected independently. A lot of the data I have read has been collected by groups affiliated with partnerships or with a vested interest in a partnership. If I relied on the ongoing existence of a partnership to pay my mortgage every month I'm hardly likely to produce statistics that show the SCP are ineffective.

Bing o

15,184 posts

250 months

Thursday 9th August 2007
quotequote all
MilnerR said:
Just making sure that you weren't guilty of not giving weight to a very important factor when comparing such small data sets. Although I agree that shouting rttm at every stat is not helpful.

We do need more data, but it has to be data collected independently. A lot of the data I have read has been collected by groups affiliated with partnerships or with a vested interest in a partnership. If I relied on the ongoing existence of a partnership to pay my mortgage every month I'm hardly likely to produce statistics that show the SCP are ineffective.
Same as anti-camera groups are unlikely to produce statistics in the scamera's favour...

TBH, I've seen enough ranting and abusive tactics from Paul Smith and his SS accolytes on other web forums to make me doubt BOTH messages.

We need long term empirical measurements over a meaningful period of time to measure the success or otherwise of scameras from independent researchers WITHOUT an agenda (if that is possible). Whilst, as a motorist, and a victim, I despise scameras, if they do play a part in road safety, I would like to know.

The same as if they don't, I would like to know even more... smile

Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
Bing o said:
MilnerR said:
Just making sure that you weren't guilty of not giving weight to a very important factor when comparing such small data sets. Although I agree that shouting rttm at every stat is not helpful.

We do need more data, but it has to be data collected independently. A lot of the data I have read has been collected by groups affiliated with partnerships or with a vested interest in a partnership. If I relied on the ongoing existence of a partnership to pay my mortgage every month I'm hardly likely to produce statistics that show the SCP are ineffective.
Hear Hear. A very balanced viewpoint if I may say so.

Well said that man.

BFF




Edited by Big Fat F'r on Thursday 9th August 14:16

smeggy

3,241 posts

270 months

Thursday 9th August 2007
quotequote all
Big Fat F'r said:
MilnerR said:
Big Fat F'r said:
smeggy said:
Oh the unadulterated joy of regression to the mean.

BFF
Speaking professionally, regression to the mean is an important factor when claiming anything about effects of a particular variable. Especially when the numbers and time points used are as limited as this. Could you please explain your apparent problem with regression to the mean?
Speaking professionally, I have absolutely no problem with regression to the mean. I understand it, and take account of it, in various tasks.

I do however have a problem with anyone who uses RTTM to dismiss all changes on any process. That is not directed at anyone in particular, just those that shout “have you not heard of RTTM” whenever we talk about cameras, as if it somehow magically explains away any change as down to chance.

As I said, we need more data to prove, or disprove, many of the things claimed on here – by both sides.

BFF
Don't tell that to us........

David Frampton manager of the WSSCP said:
Nothing else has changed on the motorway since they were introduced. There are no extra police patrols, only the cameras, and we have fewer collisions, so we have to draw some conclusions.
rolleyes

Big Fat F'r

1,232 posts

237 months

Thursday 9th August 2007
quotequote all
smeggy said:
Big Fat F'r said:
Big Fat F'r said:
smeggy said:
Oh the unadulterated joy of regression to the mean.

BFF
As I said, we need more data to prove, or disprove, many of the things claimed on here – by both sides.

BFF
Don't tell that to us........

David Frampton manager of the WSSCP said:
Nothing else has changed on the motorway since they were introduced. There are no extra police patrols, only the cameras, and we have fewer collisions, so we have to draw some conclusions.
rolleyes
Oh, I agree that both sides have often misinterpreted, lied, twisted and generally mis-used data to support their claims. But they would. Thats what people do. Study Deming et al and you will see many instances of how the reward system, and hierarchy of needs, means we want to use anything that supports us. I believe that we should accept that everyone is doing it, accept that it may be for different reasons (some of which may be innocent and genuine) and then work around it.

This obviously does not apply to YellowCorsa Scuffers, who should all just be banned for being unskilled d!ickheads who disagree with the facts. G!ts, the lot of 'em.

BFF



Edited by Big Fat F'r on Thursday 9th August 17:18

MilnerR

8,273 posts

289 months

Thursday 9th August 2007
quotequote all
I sent an email to my local partnership asking them to detail the statistical techniques used and what their null hypothesis was regarding the effect of cameras. I got a reply with the raw data for last year and this year and a statement saying accidents had dropped by 13% since last year. I replied explaining that I understood how statistics worked and that these data are completely meaningless, to which they replied that they had already supplied the requested data and were not prepared to enter into correspondents. With attitudes like that it is hardly surprising that those of us who are skeptical about camera efficiency are forced to make less than objective conclusions!

I agree that neither side of the debate are objective, however the partnership's employees have a lot more to lose if their arguments are found wanting (especially with mortgage rates on the increase), ergo I find myself less able to believe what they have to say.

smeggy

3,241 posts

270 months

Thursday 9th August 2007
quotequote all
Big Fat F'r said:
Oh, I agree that both sides have often misinterpreted, lied, twisted and generally mis-used data to support their claims.
Could I ask who our ‘other side’ is and how they’ve often misinterpreted, lied, twisted and generally mis-used data?

Regardless, you wouldn’t expect such behaviour from a supposedly professional, government affiliated organisation, not least one whose policies are working, would you?

oldsoak

5,618 posts

233 months

Thursday 9th August 2007
quotequote all
"The other side" in this instance I understand to be is that whose argument is the opposite or different to another. You support the SS ethos some don't, those 'some' are the other side...likewise to 'some', SS is the other side...If the cap fits...wear it.

fluffnik

20,156 posts

258 months

Thursday 9th August 2007
quotequote all
Big Fat F'r said:
smeggy said:
Oh the unadulterated joy of regression to the mean.
Thing is:

Road fatality rates are so low compared to the integer data that without RTTM there is nothing of statistical significance to be found.

The figures quoted by the SCPs for small areas over short times contain only noise not information.

Chrispy Porker

17,740 posts

259 months

Thursday 9th August 2007
quotequote all
I would have thought that if the stats did not support the SCP then they would say ' Ah well, we obviously need more cameras to cut down the carnage'

fluffnik

20,156 posts

258 months

Thursday 9th August 2007
quotequote all
MilnerR said:
We do need more data
Ummmm...

Since each datum in this system is a dead or mangled person I'd settle for less data even if it makes statistical analysis trickier.