# Startup says that it can detect tendencies for things like terrorism through facial analysis. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 25, 2016, 1:20pm UTC](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655 "2016-05-25T13:20:30Z")\ **Posts on this page:** 4\ **Page:** 3
**Author:** ![Doctor\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doctor_jackson/32/32_2.png) [@Doctor\_Jackson](https://boards.straightdope.com/u/Doctor_Jackson)\ **Post date:** [May 26, 2016, 2:43pm UTC](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655/41 "2016-05-26T14:43:16Z")
> [@Lemur866](#): > > If the device really were 80% accurate (which, you know, it isn’t) and you point it at everybody who walks through the airport then 1 in 5 people would be flagged as a terrorist. > > If you screen 10,000 people in a day, then you you’ve identified 2000 people as potential terrorists. How many terrorists actually try to walk through the airport every day? Let’s say it’s 1. And so now you’ve got 1 guy correctly identified as a terrorist, and 2000 people incorrectly identified as a terrorist. How do you now pick the one guy out of 2000? I guess you’re slightly better off than when you were trying to pick 1 guy out of 10000. > > But only slightly. An 80% accuracy rate does not mean it identifies 20% of the overall population as suspect, that would be a 20% hit rate (or an 80% pass through rate). Accuracy means that 80% of the suspects identified fit the criteria. Setting aside the “how good is the criteria?” question for this exercise, 'cause it likely stinks, we move to phase 2. Statistical sampling is how to narrow the field further. If this worked (again, it doesn’t - we’re just pretending for argument sake) it would identify 80% of the scanned population that fit the criteria for “terrorist”. We don’t know the match “classifiers” so we can’t know ho many people that 80% would include, but let’s say the classifications were broad and it did identify 2,000 of 10,000 as suspect. Then, even without other criteria to narrow the selection algorithm, security would randomly pick a statistically valid sample from that pool. If a 95% confidence level is good enough, that would mean security would flag 323 people for the detailed search. If you want a 99% confidence level, select 499 people. By using semi-effective screening criteria airport security could, by looking closely at 3-5% of the overall population (which is what Israel does), be much more efficient in their efforts than randomly selecting from the whole passenger base (like the US does). It is, absolutely, profiling and what constitutes valid criteria is the vexing question. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [May 26, 2016, 2:49pm UTC](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655/42 "2016-05-26T14:49:48Z")
> [@buddha\_david](#): > > If this product actually worked, a nice application would be to route all the pedophiles and terrorists onto their own separate plane. A nice solution for everyone. Except for the crew of the plane. ---
**Author:** ![Just\_Asking\_Questions](https://avatars.discourse-cdn.com/v4/letter/j/ba9def/32.png) [@Just\_Asking\_Questions](https://boards.straightdope.com/u/Just_Asking_Questions)\ **Post date:** [May 26, 2016, 3:01pm UTC](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655/43 "2016-05-26T15:01:19Z")
> [@davidm](#): > > Except for the crew of the plane. You pick the pilots that fly drunk, and the suicidal. Just left with the cabin crew. Maybe they can stay home that day. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 26, 2016, 4:34pm UTC](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655/44 "2016-05-26T16:34:58Z")
What the fuck is a “potential terrorist”-how does work when they’re gathering the stats to promote their machine? “The suspect has been identified as a potential terrorist!” “We checked him out-no priors, no suspicious contacts. Do we count this as a ‘fail’?” “Of course not. He could still _become_ one in the future-he is still a ‘potential’ terrorist.” [Previous page](https://boards.straightdope.com/t/startup-says-that-it-can-detect-tendencies-for-things-like-terrorism-through-facial-analysis/755655.md?page=2)