> I wish as technology becomes available which could be used for more Orwellian surveillance someone stood back and thought about ways it could be used for good rather than defending some absurd fear of terrorist attacks.
The issue is the fact that a "binary test" has 4 outcomes.
The good ones:
Test says "True X" and "X is true".
Test says "False X" and "X is false".
The bad ones:
Test says "True X" and "X is false".
Test says "False X" and "X is true".
Some of these can be problematic depending upon what "X" is, what the response to "X" is, what the probability of "X" is in the population, and what the probability of the "false positive" of "X" is.
In medical, this can pose a real dilemma.
At any individual test let's call the diagnosis rate 1%. If the false positive rate is about 1%, we are diagnosing one person who has "X" along with diagnosing one person who doesn't have it.
Not too bad, right? Ummmm ...
If "X" was heart disease, sure. Most of the interventions for heart disease are things like fix your diet, get some exercise, quit smoking, etc.
If "X" is breast cancer, not so much. Interventions for cancer start with something like a biopsy which can have lots of complications (hematomas, secondary infections, etc.). In addition, a cancer may not spread, or something else may kill the patient before if you left it alone.
So, the damage done in the response determines how low the false positive rate has to be.
In addition, there is a psychological aspect to a diagnosis that a lot of people overlook. A false positive for "heart issue" on your wristband can upset certain people so badly that it causes an issue.
And I haven't even started talking about the false negative rate problems. What will you do when people start saying: "Nah. I don't need to go to the doctor, my Apple watch isn't flagging anything."
This is why this kind of stuff gets deployed for "terrorism" first because there isn't any consequence to the manufacturers whether they're right or wrong--so they don't care about the relative probabilities. The fact that some random schmuck gets detained and searched isn't the manufacturers problem.