Skip to comments.What if Airport Screeners Checked Your Square Root?
Posted on 11/20/2010 4:27:54 PM PST by Diana in Wisconsin
(A computer scientist argues that racial profiling is less effective than random searches, but says simple math could offer an even better solution.)
What if airport screeners looked at would-be passengers and instead of assessing the color of their skin, asked: "What's the square root of your likelihood of being a terrorist?"
Such is the world imagined by an American computer scientist who argues that racial profiling to root out potential terrorists is actually less effective than random searches, but says some simple math could offer a better solution.
"When you have any profiling at all, it quickly becomes less effective than random sampling," said University of Texas professor William Press, whose paper appears Wednesday in the journal Significance, a publication of Britain's Royal Statistical Society.
Profiling does not work because "you end up screening the same innocent people over and over again, just because they happen to be in a profiled group," Press said.
Previous studies have shown that any apparent rise in success due to racial profiling is actually due to increased levels of law enforcement. More police focusing on one group will catch more criminals since fewer police and resources are focused on other groups.
"It is simply better to do uniform random sampling, which means everyone who shows up at the airport should have the same chance of being screened in the same way," said Press, who has written on the topic before for the Proceedings of the National Academy of Sciences.
But he has come up with an idea that just might be even better.
"It is this thing called square root sampling," he told AFP.
That way, screeners would approach a given group deemed to be, say 100 times more likely to be harmful, and then check them the square root of that number, or 10 times, more often.
"That actually would be better than uniform (random) sampling. The trouble is there is no good way to do that."
Press teaches university-level statistics and uses the example for his students, who do not argue with his mathematical formulas but do puzzle over practical ways to solve the problem in real life.
"One could imagine a system in which people's risk factors are evaluated and as you show up in airport you know, in some computerized automatic way the computer flashes either red or green and does this square root business which would be some form of optimal profiling," he said.
"But I don't know anyone who actually thinks you could make such a system work."
And when it comes to the latest controversy roiling U.S. airport travelers systems that can peer through clothing and show bodily details Press has just one hope in mind for any new screening technology.
"That it not slow down the lines," he said.
Mmmmm. Don’t forget the mayo for moi! ;-)
Profiling does not work because “you end up screening the same innocent people over and over again, just because they happen to be in a profiled group,” Press said.
So what? Statisticlly you have a much higher percentage of likelihood of finding a terrorist.
Also, We are talking of small group of people here. All Islamists cannot be more than 5% of the population no matter what color. And skin is not as important as religious affiliation.
The problem is TSA batting average is zero. The number of terrorists detected by TSA = 0, the number arrested = 0, the number convicted = 0.
The number of terrorists detected by passengers on an airplane and missed by TSA = 3 (or similar number)
We'd get down to that 5% instantly with FEW exceptions ~ and even the American from California who "went over" is from a Jewish family so he'd probably fit that physical profile himself.
I had an interesting flight one time, coming back from a conference in Houston to New York. A young lady also flying back from the conference was in the seat next to me, and she asked if I minded if she held onto my arm when we landed, because she had had a very bad experience earlier that year, and she felt very nervous about landing.
It seems that her plane crashed at the airport in Rome. It broke in two, and everyone in the other half was burned up.
I said, yes, of course, by all means take my arm.
So, as we came in for a landing, she held my arm and buried her face in my jacket. And just as we were touching down, she bit my arm. Hard.
Oh, well, glad to be of service.
It is NOT just EL AL in Israel! We flew out of Israel on Continental and were GRILLED....I think because we had gone to Jordan also.....man it was Close Contact Grilling, but I was OK because there was No touching...just asking questions and looking us in our eyes...and my husband is JEWISH!!
Bingo!! BINGO!!!!! Don’t let Muslims FLY!!
Were this a case of "logical" terrorists, the 1% might be deterred. But when talking about religious fanatics, the same logic doesn't apply.
Yes, if you consider advertising the food stamps program on AM radio as profiling. The program has either been over-funded or its demand over-estimated, so instead of cutting back on the service they are advertising for more customers.
This would be a good thread for a link to the video series about cats and engineers...
I’m not sure we know what TSA’s track record is. We do know they seem to frisk a lot of people who are highly unlikely to be terrorists.
Take out their friends; take out them. That last guy may still want to kill somebody, but if he can't buy a ticket, can't get ingredients for a bomb, or even hitch a taxiride to the airport, you've taken him out too.
There are many different working systems. Taking something like ‘place in line’, works so long as you believe that terrorists are randomly distributed across the sample. If that’s not the case, then random sampling won’t produce random outcomes.
This is the problem with random sampling is that it does nothing to combat systematic error. Fr’instance. My old planting boss used to assign the best planters, the pieces in the open that were easily accessible. He also assigned the new folks, the horrible, back of the line places. Why? He knew that the inspectors were more likely to check the easy pieces.
The same is true of the terrorist systems in place now. Checking every 11th person will nab some of the terrorists.
However, it’s more effective to profile. Had the inspectors profiled me, they would have found more errors than with the experienced planters. They also wouldn’t have to look as hard. The same is true of Muslims. Most terrorists are Muslims. Enough so to justify 1 out of every 4 searches being of a non-muslim. You combat systematic error by slanting your searches to target the error.
I’m not familiar with the in-motion equipment you reference, but their existence wouldn’t surprise me. I find your paradym of quality control interesting, definitely worthy of more thought.
We don’t need to know anyone’s religion if we know what their ears and noses probably look like, what the reflectivity of their skin is in various colors, and their weight and volume compared to their apparent skeletal proportions.
I disagree. Islam is growing quickly and racial characteristics will not be the only definingn feature of a bomber.
Then I'd probably fly much more often.........
That’s assuming their support structure are also people intending to become in-flight bombs. The bomb maker, for one, has value beyond mule-dom. Similarly, others with actual talents will serve only as support staff to the mules. Also, where does the 1% fall? If the 1% occurs near the beginning, the resulting deaths will be encouragement, and may increase the quantity of willing dupes.
I didn’t say it was.
Back in 2003, our cruise ship docked at Haifa. Mossad and other security agents came on board and interviewed every single person, some 1200 passengers. Some families, like ours, was sent for additional screening because my SCOTTISH surname ‘sounds’ Arabic as it ends with an “eeee” sound. Wife and daughter were going ashore and I was staying back. They were very curious as to why all of us weren’t taking the tour.
Wife and I had discussed this tour and IF something went “wrong” we had decided that one parent would stay back. She wanted to see the Biblical sites so I stayed back
When they asked me why I wasn’t touring, I wasn’t about to tell them the real reason...so I just said I was tired and was going to read.
Later, I wanted to just get off the ship and walk around the pier. NOPE, not on the approved debarkation list. When I said I just wanted to walk around, the guard just opened up his leather jacket enough for me to see the Uzi...I went back up the gangplank in a hurry.
I think we should hire the Israelis to train our people and do it quickly. Problem Solved.
Then, why would one want to tell Israel?