CO -Police Stop, Handcuff Every Adult at Intersection

[sjfcontrol]

I think you need to review your statistics notes...

But welcome to the forum, anyway!

Sent you a PM with my thinking. Interested in your thoughts. Ed

Working on it...

[VMI77]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

So...statistically the same chance of being exactly the third car searched is what you're saying...

Well, each car has a 5% chance, if that's what you mean. However, there is a 10% chance that the BG will be found in the first 2 cars, 15% in the first 3, etc. By the time you've searched 10 (of the 20) you have a 50/50 chance of having found the culprit. By the time you get to the last car, you have a 95% probability of already having found him. Understand?

But as you said earlier, that is just raw probability, absent any other information that could be used to increase the chances of finding the perp sooner. So, either they just started at one end and worked to the other, or they surveyed all the vehicles and determined the perp's vehicle was the least suspicious of the 20. It seems to me that the most efficient search procedure would be to eliminate the least likely contenders, such as couples, the elderly, vehicles with children, vehicles with pets, etc, and search the most likely vehicles first, such as vehicles with single males. You'd think experience would greatly increase the odds of finding the perp in one of the first vehicles searched.

[sjfcontrol]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

So...statistically the same chance of being exactly the third car searched is what you're saying...

Well, each car has a 5% chance, if that's what you mean. However, there is a 10% chance that the BG will be found in the first 2 cars, 15% in the first 3, etc. By the time you've searched 10 (of the 20) you have a 50/50 chance of having found the culprit. By the time you get to the last car, you have a 95% probability of already having found him. Understand?

But as you said earlier, that is just raw probability, absent any other information that could be used to increase the chances of finding the perp sooner. So, either they just started at one end and worked to the other, or they surveyed all the vehicles and determined the perp's vehicle was the least suspicious of the 20. It seems to me that the most efficient search procedure would be to eliminate the least likely contenders, such as couples, the elderly, vehicles with children, vehicles with pets, etc, and search the most likely vehicles first, such as vehicles with single males. You'd think experience would greatly increase the odds of finding the perp in one of the first vehicles searched.

Yes, I was calculating raw probabilities. There SHOULD HAVE BEEN some pre-screening, making it the last car even LESS likely.

[XinTX]

I was told there would be no math.............

[sjfcontrol]

I was told there would be no math.............

Pop Quiz!

[VMI77]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

So...statistically the same chance of being exactly the third car searched is what you're saying...

Well, each car has a 5% chance, if that's what you mean. However, there is a 10% chance that the BG will be found in the first 2 cars, 15% in the first 3, etc. By the time you've searched 10 (of the 20) you have a 50/50 chance of having found the culprit. By the time you get to the last car, you have a 95% probability of already having found him. Understand?

But as you said earlier, that is just raw probability, absent any other information that could be used to increase the chances of finding the perp sooner. So, either they just started at one end and worked to the other, or they surveyed all the vehicles and determined the perp's vehicle was the least suspicious of the 20. It seems to me that the most efficient search procedure would be to eliminate the least likely contenders, such as couples, the elderly, vehicles with children, vehicles with pets, etc, and search the most likely vehicles first, such as vehicles with single males. You'd think experience would greatly increase the odds of finding the perp in one of the first vehicles searched.

Yes, I was calculating raw probabilities. There SHOULD HAVE BEEN some pre-screening, making it the last car even LESS likely.

It's especially confusing to me, since we often hear how police experience tells them when something looks or seems out of place, justifying a stop or a search, but they have to search through 19 vehicles stopped at an intersection to find the BG in vehicle number 20. That can mean only one of two things --they either did no pre-screening whatsoever, which makes no sense to me, or they perceived everyone else they searched to look more like a bank robber than the actual BG --which I find rather disturbing, as I'm pretty certain I, with no law enforcement experience, could have ordered the search in such a way as to find the bad guy in at least the first half of the vehicles searched instead of the last half.

[ScooterSissy]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

Notice the wording. They didn't say he was in the last car at the light. They said he was in the final car searched. Statistically, I find it almost a certainty that he would be in the last car searched (if it's there). Once they found him, why would they continue searching?

[sjfcontrol]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

Notice the wording. They didn't say he was in the last car at the light. They said he was in the final car searched. Statistically, I find it almost a certainty that he would be in the last car searched (if it's there). Once they found him, why would they continue searching?

I disagree. I did notice the wording. It was the final car where they found him. It was the search of the final car -- not the final search of a car.
You're free to disagree, but that is the way I believe it reads, and was intended. Besides, it would be stupid to report that they found him in the last car that was searched. Of course they did, unless they continued the search after finding him.

[ScooterSissy]

If I had been in that intersection (and it had been in Texas), they would have found a loaded gun actually on my person. Would THAT have been enough evidence to arrest ME for the bank robbery, too?

Did they find the money? Or just the guns?

Its also curious that "... it wasn’t until the final car was searched that police apprehended the suspect." That's statistically unlikely. Out of 20 cars, there is only a 5% chance that the one they're looking for would be in the very last one. 95% chance that it would have been one of the other ones searched first. (Assuming an even distribution of probability for each vehicle.)

Notice the wording. They didn't say he was in the last car at the light. They said he was in the final car searched. Statistically, I find it almost a certainty that he would be in the last car searched (if it's there). Once they found him, why would they continue searching?

I disagree. I did notice the wording. It was the final car where they found him. It was the search of the final car -- not the final search of a car.
You're free to disagree, but that is the way I believe it reads, and was intended. Besides, it would be stupid to report that they found him in the last car that was searched. Of course they did, unless they continued the search after finding him.

I see the wording - "it wasn’t until the final car was searched that police apprehended the suspect", and would have to say it's ambiguous at best.
As far as "stupid to report", I'd see your point if the media seldom resorted to stupid reporting.

[johncanfield]

LEO might have been clearing the entire scene and not assuming there was one BG in one vehicle.

[jmra]

I think that you have to factor into the probabilities that the BG was not in any of the 20 cars. In fact all we know is that they arrested someone who had two guns in the car. To say at this point based on that information this was the BG they were looking for is very speculative. Unless of course they found more evidence in the car.
In short, If you are calculating the probabilities before the search began, you have to factor the probability that none of he cars contain a BG. This changes the statistics dramatically.

[sjfcontrol]

I think that you have to factor into the probabilities that the BG was not in any of the 20 cars. In fact all we know is that they arrested someone who had two guns in the car. To say at this point based on that information this was the BG they were looking for is very speculative. Unless of course they found more evidence in the car.
In short, If you are calculating the probabilities before the search began, you have to factor the probability that none of he cars contain a BG. This changes the statistics dramatically.

I mentioned to somebody offline the following regarding the existence of the BG in the last car...

My thought regarding the 'last car' was that it became obvious near the end of the search, that they weren't going to find the robber, so they added the last car, with an undercover cop as a 'plant'. They "arrest" the plant, and everybody's happy. Better than having a street-full of angry, frustrated people delayed by hours with negative results from the searches. Don't have any evidence of that, just seemed like a possibility.

I don't think adding the possibility that the BG didn't exist changes the odds all that much. The odds of the BG being in the last of 20 cars is 5% if he exists, or 0% if he doesn't. In either case, it is unlikely they'd legitimately find him in the last car.

[jmra]

I think that you have to factor into the probabilities that the BG was not in any of the 20 cars. In fact all we know is that they arrested someone who had two guns in the car. To say at this point based on that information this was the BG they were looking for is very speculative. Unless of course they found more evidence in the car.
In short, If you are calculating the probabilities before the search began, you have to factor the probability that none of he cars contain a BG. This changes the statistics dramatically.

I mentioned to somebody offline the following regarding the existence of the BG in the last car...

My thought regarding the 'last car' was that it became obvious near the end of the search, that they weren't going to find the robber, so they added the last car, with an undercover cop as a 'plant'. They "arrest" the plant, and everybody's happy. Better than having a street-full of angry, frustrated people delayed by hours with negative results from the searches. Don't have any evidence of that, just seemed like a possibility.

I don't think adding the possibility that the BG didn't exist changes the odds all that much. The odds of the BG being in the last of 20 cars is 5% if he exists, or 0% if he doesn't. In either case, it is unlikely they'd legitimately find him in the last car.

It changes the odds because if you rightly assume that the BG may not be in one of the 20 cars then you are no longer limiting the probabilities to 20 cars. You would have to calculate how far the BG could have traveled in every route available to him. Then you would have to estimate the total number of vehicles in that area. Then you would use that number in relationship to the 20 cars that were stopped to determine the probability that he was even in one of the 20 cars. Unless of course you believe that the tip was iron clad.

[sjfcontrol]

It changes the odds because if you rightly assume that the BG may not be in one of the 20 cars then you are no longer limiting the probabilities to 20 cars. You would have to calculate how far the BG could have traveled in every route available to him. Then you would have to estimate the total number of vehicles in that area. Then you would use that number in relationship to the 20 cars that were stopped to determine the probability that he was even in one of the 20 cars. Unless of course you believe that the tip was iron clad.

Well, that's obviously a different problem all together. Conceptually that could then involve the search of every car in the entire town -- and that assumes that they could throw up road-blocks at all egresses before the vehicle could have exited the town. Now we're just getting silly (not that the original solution wasn't). There's no way they could stop everybody in a vehicle in the whole town. There wouldn't be enough cops (or handcuffs, for that matter). Seems to me they either had to find him at the intersection in question, or he was 'in the wind'.

[jmra]

It changes the odds because if you rightly assume that the BG may not be in one of the 20 cars then you are no longer limiting the probabilities to 20 cars. You would have to calculate how far the BG could have traveled in every route available to him. Then you would have to estimate the total number of vehicles in that area. Then you would use that number in relationship to the 20 cars that were stopped to determine the probability that he was even in one of the 20 cars. Unless of course you believe that the tip was iron clad.

Well, that's obviously a different problem all together. Conceptually that could then involve the search of every car in the entire town -- and that assumes that they could throw up road-blocks at all egresses before the vehicle could have exited the town. Now we're just getting silly (not that the original solution wasn't). There's no way they could stop everybody in a vehicle in the whole town. There wouldn't be enough cops (or handcuffs, for that matter). Seems to me they either had to find him at the intersection in question, or he was 'in the wind'.

Remember we are discussing probabilities, not practicalities. If you want to calculate the probability of the BG being in one of the 20 cars (without giving credence to the tip) you can't ignore the probability that he wouldn't be there at all. It may be silly to you but you can't properly calculate the probability any other way.
Now, if you want to qualify that the tip assures that one of the 20 cars contains the BG, then that is a different story.