Question about Police Lidar Standard Deviations

[Hacp]

So I went through the whole thread and no one provided any useful data for me. There were a few responses that were not helpful and I'll reply to them.

You already said you were going 65 and with the flow of traffic. You admitted guilt! You're a liar!

I said I like to keep below 65 for fuel economy reasons. My car runs efficient in the range of 45-65 mph. So if the speed limit is 75, I like to be below 65. I was most likely going 55 mph and possibly even 45 mph based on data from google maps.

I used LIDAR and it's accurate! Believe me!

What you said can not be quantified.

Don't bring charts/etc to court

I plan to keep it under 5 minutes.

 

[gorcorps]

https://youtu.be/cc3Um-BBhpI

(I know everyone here hates the show, but seriously this is the OP to a T)

 

[Ferzerp]

I've heard this in traffic court its irrelevant because the cop could only pull over one.

Yeah, but he can radio his buddy to pull over another. Ask me how I know. :/

 

[Fanatical Meat]

So I went through the whole thread and no one provided any useful data for me. There were a few responses that were not helpful and I'll reply to them.



I said I like to keep below 65 for fuel economy reasons. My car runs efficient in the range of 45-65 mph. So if the speed limit is 75, I like to be below 65. I was most likely going 55 mph and possibly even 45 mph based on data from google maps.



What you said can not be quantified.



I plan to keep it under 5 minutes.

You've gotten good information just not the information you hoped for.
I'd show up, dress professionally, don't act like the smartest guy in the room, be respectful and especially be respectful of everyone's time.

 

[Fanatical Meat]

Yeah, but he can radio his buddy to pull over another. Ask me how I know. :/

I know the point is if two are speeding and one is pulled over it doesn't change the fact that one was speeding. The Police aren't under any obligation to pull over 100% of the people speeding 100% of the time.

 

[Eli]

Nobody can give you any information about specific tolerances without knowing the model of device that was in use...

I did find this.. lots of math.

http://copradar.com/preview/chapt2/ch2d1.html

Knock yourself out. Maybe you should subpoena the state so you can figure out the angle the cop was holding the gun at, and how far away he was when he zapped you, so you can give the judge a math lesson? I'm sure that would go over well. lol

I think it's fine that you're taking this seriously.. but perhaps it's a little too seriously...

 

[Ferzerp]

I know the point is if two are speeding and one is pulled over it doesn't change the fact that one was speeding. The Police aren't under any obligation to pull over 100% of the people speeding 100% of the time.

Which of course is more evidence that revenue is the concern and not safety as claimed.

 

[kinev]

Thanks. If you have further details please provide it.

I was clocked going 73mph on a 55mph speed limit. I was not looking at the speedometer at the time so I don't know my actual speed. I was following the car ahead of me and cars usually go at the speed limit on this piece of the highway since police are always there!

I try to keep below 65mph all the time for fuel efficiency reasons. In this section of the road I keep AT the speed limit so 55mph. 73 mph is far too high.

My strategy is simple. First I will establish that I am an excellent driver with no previous violations. Next I will establish that I had no inventive or motive to speed, there's actually a disincentive for speeding (gas mileage)!

I will then show evidence that I was averaging far below the speed limit based on the time I left work, average time it takes to go from my chair to my car, and time it takes for my car to leave work and arrive at the spot I was LIDAR'd. I will provide written evidence form my boss on the time I left work since he was there the exact moment I left my chair. I will use google maps to show how I was averaging below the speed limit.

Finally I will bring up the LIDAR confidence interval defense. Because I had no incentive to speed, because I am a safe drive, and because of the possibility of false positives in LIDAR, there is reasonable doubt that I was going above the speed limit.

I am going to provide a well researched argument based on evidence I have gathered. I would hope the judge would appreciate that I am taking this seriously.

Saw your name is pulsar. Would you have more info on LIDAR quality data? I saw that google was working on their own LIDAR device for self driving cars. Any google employees want to hook me up with non-confidential data?

Guys, he had his day in court already and we, luckily, found the surveillance video:

edit:
Dangit! gorcorps beat me to it...
X(

 

[DrPizza]

So I went through the whole thread and no one provided any useful data for me. There were a few responses that were not helpful and I'll reply to them.

I hope this is helpful: you seem to be misapplying mathematics. A bell curve and standard deviations are models, and do not necessarily fit reality the way you seem to think it does. If you roll two dice, the average value of the sum of the dice is 7. The standard deviation is 2.412. You seem to be misusing/abusing mathematics to make the claim that because the standard deviation is 2.412, that roughly 2% of the time that I roll two dice, I'm going to get a total greater than 12. Even if you can find a mean and standard deviation for LIDAR, that does not imply that the data fits a bell curve perfectly. There's no reason to suspect that routinely, as a certain percentage of trials, the data is going to be off by as much as you claimed. The distribution of actual LIDAR differences from actual is only approximated by a normal distribution.

As I said to someone earlier, there have been plenty of times in my life where I've been driving and just sort of zoned out - I was merely keeping pace with the other traffic on the road. I looked down and thought, "holy shit!" and slowed down, because I never intentionally go more than 8 or 9 mph over the speed limit. I suspect you had one of those moments. Also, and I've been wondering this for a while, how the hell, when you see a police car, do you not at least glance at your speedometer?

 

[Hacp]

I hope this is helpful: you seem to be misapplying mathematics. A bell curve and standard deviations are models, and do not necessarily fit reality the way you seem to think it does. If you roll two dice, the average value of the sum of the dice is 7. The standard deviation is 2.412. You seem to be misusing/abusing mathematics to make the claim that because the standard deviation is 2.412, that roughly 2% of the time that I roll two dice, I'm going to get a total greater than 12. Even if you can find a mean and standard deviation for LIDAR, that does not imply that the data fits a bell curve perfectly. There's no reason to suspect that routinely, as a certain percentage of trials, the data is going to be off by as much as you claimed. The distribution of actual LIDAR differences from actual is only approximated by a normal distribution.

You did not read the part where I asked if anyone had distribution curves. So no, I am not misapplying math. Thanks!

Thanks for all the comments and I appreciate it. It looks like the LIDAR companies have purposely made data I seek difficult to collect. Sad!

 

[Fanatical Meat]

Which of course is more evidence that revenue is the concern and not safety as claimed.

Well one is still stopped.

 

[Eli]

As I said to someone earlier, there have been plenty of times in my life where I've been driving and just sort of zoned out - I was merely keeping pace with the other traffic on the road. I looked down and thought, "holy shit!" and slowed down, because I never intentionally go more than 8 or 9 mph over the speed limit. I suspect you had one of those moments. Also, and I've been wondering this for a while, how the hell, when you see a police car, do you not at least glance at your speedometer?

I suspect this as well, but that's why I asked what kind of car he has. It's very easy to do in a modern, powerful car.

But I'm usually driving an Insight. It would be fairly difficult to get it up to 70+mph without realizing it, you'd have to be off in lala land for quite some time... or with your foot to the floor.

 

[Capt Caveman]

I plan to keep it under 5 minutes.

They're not going to give you 5 minutes. Be lucky if you have two minutes.

 

[zinfamous]

https://youtu.be/cc3Um-BBhpI

(I know everyone here hates the show, but seriously this is the OP to a T)

It's uncanny.

 

[DrPizza]

You did not read the part where I asked if anyone had distribution curves. So no, I am not misapplying math. Thanks!

Thanks for all the comments and I appreciate it. It looks like the LIDAR companies have purposely made data I seek difficult to collect. Sad!

You want distribution curves? How about "they are accurate, and never off by 10mph."

You want: http://www.nhtsa.gov/About+NHTSA/Tr...fications+for+LIDAR+Speed+Measurement+Devices

If you read that article, it should give you sufficient search terms to find exactly what you're looking for. (I'm on a device that doesn't like pdfs too much, or I'd dig deeper.) Nonetheless, if it's ever over by 10mph - it doesn't matter if it's once per 100 times, or once per 1000 times, the device would fail the NHTSA's performance specifications. It can read a lower speed than actual; I think someone linked the formula above. You have to be going nearly straight at it to get a "perfect" reading - if you're at an angle to lidar, it will read a *lower* speed than you're actually going.

 

[pcgeek11]

There are lots of laughs in this thread. Thanks Hacp.

 

[Captante]

So I went through the whole thread and no one provided any useful data for me.

Plenty of folks offered you useful advice based on experience in traffic-court however since it wasn't what you wanted to hear you ignored it.

Best of luck ... you'll be needing it.

 

[Meghan54]

They're not going to give you 5 minutes. Be lucky if you have two minutes.

If he starts down the road he's discussing doing, he'll be lucky to last 30 seconds before the judge says "Guilty. Pay the clerk."

 

[MixMasterTang]

If he starts down the road he's discussing doing, he'll be lucky to last 30 seconds before the judge says "Guilty. Pay the clerk."

And judging by his attitude I could see him still trying to talk over the judge and getting a contempt fine.

 

[Fanatical Meat]

Marked for six month follow up

Reality is from my experience there is a 2 in 3 chance it will get dismissed before he opens his mouth.

 

[Anubis]

I have a fantastic idea

pay the ticket and move on

 

[gorcorps]

I have a fantastic idea

pay the ticket and move on

No

I want him to fight it and see what happens

 

[Linux23]

Funny! My last speeding ticket... like 10 years ago..

Maybe he only clocked the Toyota.. Then he rolls down his window, sticks his arm out and makes aggressive pointy motions towards the shoulder at me. Crap. 78 in a 55. lol

and i'd look at him, smile, and jam the throttle to the floor and see who he prefers to pull over. me or that other driver.

 

[Linux23]

You sound exactly like that skinny weirdo from the big bang theory. And here I thought the way he tried to get out of a ticket was just made up for the show, but there really are people who think this way.

Face it, you were speeding (based on your story I see no evidence to the contrary since you admit you were just keeping with the flow of traffic)

Good luck

LMFAO

https://www.youtube.com/watch?v=qOfxGR0K9jA

 

[spacejamz]

There are lots of laughs in this thread. Thanks Hacp.