I again want to highlight how you use the generic term "terrorism" as short-hand for a specific type of terrorism, specifically 'those people (in the middle east and the arab world) have had, and a common thread to those is ethnicity/religion.'

You haven't defined how to identify "those people". What ethnicity is common to Umar Farouk Abdulmutallab and Ziad Jarrah?

So you must mean religion.

Do you put Muhammad Ali and other Black Muslims from the US in the same category as "these people"? Do you distinguish "salafi/fundamentalists" from other Muslims? Some Muslims say that Ahmadiyya Islam isn't a Muslim faith. Should they be included?

How easy do you think it would be for someone to hide their religious beliefs in order to bypass your screen?

Nor have you identified the false positive rate. How many terrorists do you think there are, and how people many fit the screening category?

If you define "terrorist" to exclude anything caused by a non-Muslim (anti-abortion murderers, anti-black murderers, Irish/Basque/whatever separatist) then that's like shooting bullets at a barn then putting the target around what you hit - there are no non-Muslim terrorists because you defined it that way.

Now, I'm not saying you personally have to do this. I'm pointing out why profiling won't work. Because a quick run of the numbers shows that you will be overwhelmed by false positives.

> Did I ever give the impression that any of these weights

You gave the very strong impression that "ethnicity/religion" is on the top of the list. I've since pointed out two characteristics which are even more accurate, and you keep arguing that "ethnicity/religion" should be high on the list.

Going back to your original question, which is "I don't see what's wrong with racial profiling." My answer again is that even setting aside the morality, the economics don't work out. What's wrong is you waste money for no gain and added frustration.

> The very notion of "profiling" means you use all available info about likely attributes

Here's where I know you have little experience with data mining. Every attribute you consider adds a new dimension to your search space. But there aren't that many terrorists, we have very little data in how to train the model, and most of that data is very noisy.

Even in cases where we have lots of data, like schools, attempts to use models like VAM have produced what is at best confusing information, and at worst - and more often - is camouflage used to force certain political beliefs without real justification.

How are you so sure that screening based on ethnicity/religion will make one whit of difference? How do you measure its effectiveness? When you say "from all publicly known cases" - how many cases do you think there are? 100? 1,000? How much statistical certainty do you think we can get from that?

> That's (the "frustration of a TSA check" or similar minor event) is not historically (from all known cases) what such people have in their background.

It's illegal for the TSA to profile, so there is no such "similar minor event" to use as a reference. Which cases were you thinking of when you said "all known cases"?

What I mean are the more general examples of profiling, which have lead to anger, protests, riots, and killings. The Black Panther Party would not have started had black Americans not been routinely profiled.

Or if you prefer, we use profiling to target our cruise missiles and drone attacks. Some of those kill wedding parties, babies, and other civilians. This makes some people angry enough to want to attack the US. But of course, this isn't a "minor event" like TSA screening. It's still an example of how profiling can induce new extremism.

And again, how do you tell if a race/ ethnicity/ religion/ gender/ occupation/ nationality/ whatever screen is effective, when the base rate without such screening is zero?