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Sidewalks, bikes, & civil engineering



 
 
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  #1  
Old September 27th 11, 06:50 PM posted to rec.bicycles.soc,rec.bicycles.misc,rec.bicycles.tech
Jym Dyer
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Posts: 999
Default Sidewalks, bikes, & civil engineering

The original report at
http://phoenix.gov/STREETS/2007bike.pdf

=v= As usual, based on police reports and thus subject to
the observer bias of police and, in the case of fatalities,
survivor bias. So the "at-fault" numbers and charts are
completely meaningless, but will of course be used to prop up
the usual entrenched opinions anyhow. The other stats are of
more value, of course, though they depend on how much forensic
work the police decide to do when a bike is involved.
_Jym_
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  #2  
Old September 27th 11, 08:37 PM posted to rec.bicycles.soc,rec.bicycles.misc
Frank Krygowski[_3_]
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Posts: 1,365
Default Sidewalks, bikes, & civil engineering

Jym Dyer wrote:
The original report at

http://phoenix.gov/STREETS/2007bike.pdf

=v= As usual, based on police reports and thus subject to
the observer bias of police and, in the case of fatalities,
survivor bias. So the "at-fault" numbers and charts are
completely meaningless, but will of course be used to prop up
the usual entrenched opinions anyhow. The other stats are of
more value, of course, though they depend on how much forensic
work the police decide to do when a bike is involved.
_Jym_


When someone says "That data is useless," it's good form to give other
data that's better.

So: Got data on Phoenix? Or got other data that proves what you claim?

--
- Frank Krygowski
  #3  
Old September 28th 11, 03:18 AM posted to rec.bicycles.soc,rec.bicycles.misc
Frank Krygowski[_3_]
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Posts: 1,365
Default Sidewalks, bikes, & civil engineering

Jym Dyer wrote:
The original report at

http://phoenix.gov/STREETS/2007bike.pdf

=v= As usual, based on police reports and thus subject to
the observer bias of police and, in the case of fatalities,
survivor bias. So the "at-fault" numbers and charts are
completely meaningless, but will of course be used to prop up
the usual entrenched opinions anyhow. The other stats are of
more value, of course, though they depend on how much forensic
work the police decide to do when a bike is involved.
_Jym_



When someone says "That data is useless," it's good form to give other
data that's better.

So: Got data on Phoenix? Or got other data that proves what you claim?


--
- Frank Krygowski
  #4  
Old September 28th 11, 03:59 PM posted to rec.bicycles.soc,rec.bicycles.misc
Jym Dyer
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Posts: 999
Default Sidewalks, bikes, & civil engineering

When someone says "That data is useless," it's good form
to give other data that's better.


=v= That would be great if other data were available. If
it's not, that doesn't mean the bad data is suddenly good.
_Jym_
  #5  
Old September 28th 11, 04:44 PM posted to rec.bicycles.soc,rec.bicycles.misc
Frank Krygowski[_3_]
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Posts: 1,365
Default Sidewalks, bikes, & civil engineering

Jym Dyer wrote:
When someone says "That data is useless," it's good form
to give other data that's better.


=v= That would be great if other data were available. If
it's not, that doesn't mean the bad data is suddenly good.
_Jym_


So what you're saying is "_All_ the data is bad. I just know it is.
You just have to believe me."

Sorry. I think unquestioning faith in a self-proclaimed prophet is kind
of dangerous.

--
- Frank Krygowski
  #6  
Old September 29th 11, 06:41 AM posted to rec.bicycles.soc,rec.bicycles.misc
Jym Dyer
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Posts: 999
Default Sidewalks, bikes, & civil engineering

Frank Krygowski writes:
So what you're saying is "_All_ the data is bad. I
just know it is. You just have to believe me."


=v= What I actually said is that *part* of the data is
subject to bias: namely, the at-fault numbers.

Sorry. I think unquestioning faith in a self-proclaimed
prophet is kind of dangerous.


=v= Now you're really off the rails. I named specific and
well-known forms of bias (observer bias and survivor bias).
I did not invent these insights, I'm just applying them. If
you have any substantial, non-_ad_hominem_ reason why these
biases should simply be ignored, by all means present them.
_Jym_
  #7  
Old September 29th 11, 11:03 AM posted to rec.bicycles.soc,rec.bicycles.misc
Jim
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Posts: 3
Default Sidewalks, bikes, & civil engineering

On Sep 27, 12:50*pm, Jym Dyer wrote:
The original report at


http://phoenix.gov/STREETS/2007bike.pdf

=v= As usual, based on police reports and thus subject to
the observer bias of police and, in the case of fatalities,
survivor bias. *So the "at-fault" numbers and charts are
completely meaningless, but will of course be used to prop up
the usual entrenched opinions anyhow. *The other stats are of
more value, of course, though they depend on how much forensic
work the police decide to do when a bike is involved.
* * _Jym_


One need not go much beyond the introduction where it says "Most
bicyclists were hit from the left side while riding AGAINST TRAFFIC ON
THE SIDEWALK, ROADWAY or while crossing streets." I capitalized two
points that drive me nuts. We need to ride within the confines of the
law or we will find ourselves confined to bike trails/paths/lanes
there-by limiting where ad how people like myself can live.
  #8  
Old September 29th 11, 07:08 PM posted to rec.bicycles.soc,rec.bicycles.misc
Frank Krygowski[_3_]
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Posts: 1,365
Default Sidewalks, bikes, & civil engineering

Jym Dyer wrote:
Frank Krygowski writes:
So what you're saying is "_All_ the data is bad. I
just know it is. You just have to believe me."


=v= What I actually said is that *part* of the data is
subject to bias: namely, the at-fault numbers.


And again: Where is your evidence?


Sorry. I think unquestioning faith in a self-proclaimed
prophet is kind of dangerous.


=v= Now you're really off the rails. I named specific and
well-known forms of bias (observer bias and survivor bias).
I did not invent these insights, I'm just applying them.


But you haven't shown that it applies to the Phoenix data, or if it
does, to what degree. You can hardly expect researchers to discard all
data just because Jym Dyer thinks it might be invalid!

If you have any substantial, non-_ad_hominem_ reason why these
biases should simply be ignored, by all means present them.


Until they're demonstrated to exist, they must be ignored.

Understand, I'm not claiming all Phoenix data is faultless. I'm aware
of problems with data collection. In fact, I've corresponded
extensively with two statisticians who are recognized masters at
spotting shortcomings and bias in similar data collection.

But those individuals don't just toss all data based on the idea it may
contain bias. They are known for finding evidence of such bias, when
applicable, and using their evidence to improve the analysis of the data.

So far, you've done none of that. You've just said "Ignore that data."
So seriously, what have you got for evidence that Phoenix data is
significantly in error?


--
- Frank Krygowski
  #9  
Old September 30th 11, 03:56 PM posted to rec.bicycles.soc,rec.bicycles.misc
Opus[_2_]
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Posts: 414
Default Sidewalks, bikes, & civil engineering

On Sep 29, 1:08*pm, Frank Krygowski wrote
snip
So far, you've done none of that. *You've just said "Ignore that data."
* So seriously, what have you got for evidence that Phoenix data is
significantly in error?

--
- Frank Krygowski


Well one well-established form of bias against bicycles in wrecks is
"windshield bias" where a driver will pull "facts" out of his butt to
establish that the cyclist was at fault including the physically
impossible (Trying to beat a traffic signal that was facing away from
the rider had they been going in the direction specified in the
report, which was away from the cyclist's destination and back towards
his point of origin for that trip, in Portland. Or specifying a
physically impossible speed for the cyclist 35 MPH uphill in order to
justify a ticket against an unconscious cyclist in Tucson). One that I
am personally familiar with was a cyclist run over in Chattanooga
where they blamed the cyclist's panniers for getting caught on the
back bumper of a truck causing the cyclist to be ^thrown forward and
to the left when hit on the left side of the bike^ under the rear
wheels of the truck. Another one was a wreck in Texarkana where the
motor vehicle contacted the right side of the bike with the left
(driver's) side of the vehicle, and they tried to blame the cyclist
for "swerving from the shoulder". I have seen **** like that almost
every day for more than 5 years as I collect and post links to
articles on bike wrecks. Some of the bias is so prevalent that
acronyms have been made: SMIDSY, SWSS, SWCC... Se, yes, bias has been
well established against cyclists by LEO.
  #10  
Old September 30th 11, 05:24 PM posted to rec.bicycles.soc,rec.bicycles.misc
Frank Krygowski[_3_]
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Posts: 1,365
Default Sidewalks, bikes, & civil engineering

Opus wrote:
On Sep 29, 1:08 pm, Frank wrote
snip
So far, you've done none of that. You've just said "Ignore that data."
So seriously, what have you got for evidence that Phoenix data is
significantly in error?

--
- Frank Krygowski


Well one well-established form of bias against bicycles in wrecks is
"windshield bias" where a driver will pull "facts" out of his butt to
establish that the cyclist was at fault including the physically
impossible (Trying to beat a traffic signal that was facing away from
the rider had they been going in the direction specified in the
report, which was away from the cyclist's destination and back towards
his point of origin for that trip, in Portland. Or specifying a
physically impossible speed for the cyclist35 MPH uphill in order to
justify a ticket against an unconscious cyclist in Tucson). One that I
am personally familiar with was a cyclist run over in Chattanooga
where they blamed the cyclist's panniers for getting caught on the
back bumper of a truck causing the cyclist to be ^thrown forward and
to the left when hit on the left side of the bike^ under the rear
wheels of the truck. Another one was a wreck in Texarkana where the
motor vehicle contacted the right side of the bike with the left
(driver's) side of the vehicle, and they tried to blame the cyclist
for "swerving from the shoulder". I have seen **** like that almost
every day for more than 5 years as I collect and post links to
articles on bike wrecks. Some of the bias is so prevalent that
acronyms have been made: SMIDSY, SWSS, SWCC... Se, yes, bias has been
well established against cyclists by LEO.


I'm not doubting that there are incidents of bias. What I'm doubting is
that by citing a bias incident in Texarkana or Chattanooga, we can say
"All the data from Phoenix is worthless."

--
- Frank Krygowski
 




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