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PostPosted: Sat Aug 21, 2010 02:34 
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George,

I couldn’t help but notice your little debate with Claire today regarding camera effectiveness. I see that you quoted, from your own website, this snippet:
Tory Boy Racers
monbiot.com wrote:
A study for Penning’s department shows that 19% fewer people were killed or seriously injured at accident black spots after speed cameras were introduced, above and beyond the general decline in accidents on the roads (6).

The referenced Four Year report (6), Table H8 is the only one that contains your 19% figure. However, ...

The 4 Year Report wrote:
Table H8 gives the estimated scheme effects expressed relative to what would have been expected had the camera not been installed

The H8 data describes one portion relative to others, presented as an 'after (without) vs after (with)' comparison.
It is not describing a KSI fall using a 'before (without) vs after (with)' comparison.

Your statement of "19% fewer people were killed or seriously injured at accident black spots after speed cameras were introduced" is the 'before vs after' type statement.

Similarly, the normal stated measure of camera effectiveness, as presented by the SCPs: "There has been an xx% reduction of KSI at the camera site (compared to the 3 year baseline)" is the 'before vs after' type statement.

Only table H7 gives the necessary 'before vs after' breakdown of the KSI reduction:

The 4 Year Report wrote:
Table H7 summarises the estimated percentage changes in FSCs attributable to the effects of the cameras, RTM and trend relative to the observed FSCs prior to camera installation. The overall average observed reduction in FSCs is 55%. After allowing for trend and RTM effects, the overall average reduction in FSCs attributable to these cameras is 10% of those observed in the baseline period. RTM effects account for a fall of 35% with trend accounting for a further fall of 9%. Thus RTM accounts for about three fifths of the observed reduction in FSCs with the effects of the cameras and trend each accounting for a fifth.

- Observed change: -54.5% (the total)

- RTM effect: -34.8% (illusory benefit being discussed)
- Trend effect: -9.3% (illusory benefit - the underlying national long-term trend)
- Scheme effect: -10.4% (the genuine benefit at the site - however it is done [and 'Bias On Selection'])

As you can see, in terms of 'fewer people KSI at camera site after speed cameras were introduced', the 19% doesn't feature. Well, it does if you consider the portion of the "scheme effect" against the total fall (10.4 / 34.8+9.3+10.4 = 19%).

I guess 10% doesn't sound nearly as impressive as 19%; was the bigger number simply too tempting for you?

As Claire rightly pointed out to you George, you are trying to pass off apples as oranges!
I trust your apology to Claire will be forthcoming soon!



I so love your reaction when Claire pointed out that the Safe Speed campaign calls for roads to be enforced by trafpol instead of cameras - you literally had no answer for that :lol:



But there’s more. You obviously know about RTTM (be it in an erroneous way) from
Fast and loose [2007]:
monbiot.com wrote:
“regression to the mean”

However, in a later posting, you state:
Sending Off The Ref [2010]
monbiot.com wrote:
The department’s own studies show that deaths and injuries are reduced by 42% where cameras are deployed

So where is the compensation for RTTM?
So you’re as bad as the SCPs when spouting lies about camera effectiveness, huh? :roll:



I’ve looked through your website George. For the motoring sections, you certainly seem to focus on compliance and trusting claims from authorities, yet say surprisingly little about what makes safe driving.

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PostPosted: Sat Aug 21, 2010 18:19 
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A challenge from me to you, George!

I have emailed George informing him of these responses.

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PostPosted: Tue Aug 24, 2010 17:36 
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Are you expecting him to come here and respond?

I fear he is from the Steve Callaghan school of unanswered questions!

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PostPosted: Wed Aug 25, 2010 02:10 
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"I asked this because it is the only question which counts". I suspect he won't answer as "he fears exposure". Perhaps he will 'hate me for telling him something new'!

(all are semi-quotes from his own website)

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PostPosted: Wed Aug 25, 2010 18:43 
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I have a question for the swiveleyed one....

George, can you say, hand on heart that you in your little renault have NEVER exceeded the speed limit you hold so dear?

If you cannot, then.......




SHUT UP!

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PostPosted: Wed Aug 25, 2010 20:22 
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I saw him on the news last night objecting to the extraction of gas from shale, he may be right about it being more polluting than extraction from sandstone and I agree that renewable sources such as tidal energy are a good idea. Unfortunately his suggestion that we should be using wind power instead of gas is ludicrous, he obviously has not noticed you cannot simply switch on the wind when power demand rises.

It really just shows he cannot grasp that complex and changing systems cannot be addressed by whatever one size fits all solution meets his approval.

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