[News] Politics of Paranoia and Intimidation

[Anti-Imperialist News]

May 24, 2006


The Politics of Paranoia and Intimidation


Why Does the NSA Engage in Mass Surveillance of 
Americans When It's Statistically Impossible for 
Such Spying to Detect Terrorists?

By FLOYD RUDMIN

The Bush administration and the National Security 
Agency (NSA) have been secretly monitoring the 
email messages and phone calls of all Americans. 
They are doing this, they say, for our own good. 
To find terrorists. Many people have criticized 
NSA's domestic spying as unlawful invasion of 
privacy, as search without search warrant, as 
abuse of power, as misuse of the NSA's resources, 
as unConstitutional, as something the communists 
would do, something very unAmerican.

In addition, however, mass surveillance of an 
entire population cannot find terrorists. It is a 
probabilistic impossibility. It cannot work.

What is the probability that people are 
terrorists given that NSA's mass surveillance 
identifies them as terrorists? If the probability 
is zero (p=0.00), then they certainly are not 
terrorists, and NSA was wasting resources and 
damaging the lives of innocent citizens. If the 
probability is one (p=1.00), then they definitely 
are terrorists, and NSA has saved the day. If the 
probability is fifty-fifty (p=0.50), that is the 
same as guessing the flip of a coin. The 
conditional probability that people are 
terrorists given that the NSA surveillance system 
says they are, that had better be very near to 
one (p_1.00) and very far from zero (p=0.00).

The mathematics of conditional probability were 
figured out by the Scottish logician Thomas 
Bayes. If you Google "Bayes' Theorem", you will 
get more than a million hits. Bayes' Theorem is 
taught in all elementary statistics classes. 
Everyone at NSA certainly knows Bayes' Theorem.

To know if mass surveillance will work, Bayes' 
theorem requires three estimations:

1) The base-rate for terrorists, i.e. what 
proportion of the population are terrorists.

2) The accuracy rate, i.e., the probability that 
real terrorists will be identified by NSA;

3) The misidentification rate, i.e., the 
probability that innocent citizens will be misidentified by NSA as terrorists.

No matter how sophisticated and super-duper are 
NSA's methods for identifying terrorists, no 
matter how big and fast are NSA's computers, 
NSA's accuracy rate will never be 100% and their 
misidentification rate will never be 0%. That 
fact, plus the extremely low base-rate for 
terrorists, means it is logically impossible for 
mass surveillance to be an effective way to find terrorists.

I will not put Bayes' computational formula here. 
It is available in all elementary statistics 
books and is on the web should any readers be 
interested. But I will compute some conditional 
probabilities that people are terrorists given 
that NSA's system of mass surveillance identifies them to be terrorists.

The US Census shows that there are about 300 million people living in the USA.

Suppose that there are 1,000 terrorists there as 
well, which is probably a high estimate. The 
base-rate would be 1 terrorist per 300,000 
people. In percentages, that is .00033% which is 
way less than 1%. Suppose that NSA surveillance 
has an accuracy rate of .40, which means that 40% 
of real terrorists in the USA will be identified 
by NSA's monitoring of everyone's email and phone 
calls. This is probably a high estimate, 
considering that terrorists are doing their best 
to avoid detection. There is no evidence thus far 
that NSA has been so successful at finding 
terrorists. And suppose NSA's misidentification 
rate is .0001, which means that .01% of innocent 
people will be misidentified as terrorists, at 
least until they are investigated, detained and 
interrogated. Note that .01% of the US population 
is 30,000 people. With these suppositions, then 
the probability that people are terrorists given 
that NSA's system of surveillance identifies them 
as terrorists is only p=0.0132, which is near 
zero, very far from one. Ergo, NSA's surveillance 
system is useless for finding terrorists.

Suppose that NSA's system is more accurate than 
.40, let's say, .70, which means that 70% of 
terrorists in the USA will be found by mass 
monitoring of phone calls and email messages. 
Then, by Bayes' Theorem, the probability that a 
person is a terrorist if targeted by NSA is still 
only p=0.0228, which is near zero, far from one, and useless.

Suppose that NSA's system is really, really, 
really good, really, really good, with an 
accuracy rate of .90, and a misidentification 
rate of .00001, which means that only 3,000 
innocent people are misidentified as terrorists. 
With these suppositions, then the probability 
that people are terrorists given that NSA's 
system of surveillance identifies them as 
terrorists is only p=0.2308, which is far from 
one and well below flipping a coin. NSA's 
domestic monitoring of everyone's email and phone 
calls is useless for finding terrorists.

NSA knows this. Bayes' Theorem is elementary 
common knowledge. So, why does NSA spy on 
Americans knowing it's not possible to find 
terrorists that way? Mass surveillance of the 
entire population is logically sensible only if 
there is a higher base-rate. Higher base-rates 
arise from two lines of thought, neither of them very nice:

1) McCarthy-type national paranoia;

2) political espionage.

The whole NSA domestic spying program will seem 
to work well, will seem logical and possible, if 
you are paranoid. Instead of presuming there are 
1,000 terrorists in the USA, presume there are 1 
million terrorists. Americans have gone paranoid 
before, for example, during the McCarthyism era 
of the 1950s. Imagining a million terrorists in 
America puts the base-rate at .00333, and now the 
probability that a person is a terrorist given 
that NSA's system identifies them is p=.99, which 
is near certainty. But only if you are paranoid. 
If NSA's surveillance requires a presumption of a 
million terrorists, and if in fact there are only 
100 or only 10, then a lot of innocent people are 
going to be misidentified and confidently mislabeled as terrorists.

The ratio of real terrorists to innocent people 
in the prison camps of Guantanamo, Abu Ghraib, 
and Kandahar shows that the US is paranoid and is 
not bothered by mistaken identifications of 
innocent people. The ratio of real terrorists to 
innocent people on Bush's no-fly lists shows that 
the Bush administration is not bothered by 
mistaken identifications of innocent Americans.

Also, mass surveillance of the entire population 
is logically plausible if NSA's domestic spying 
is not looking for terrorists, but looking for 
something else, something that is not so rare as 
terrorists. For example, the May 19 Fox News 
opinion poll of 900 registered voters found that 
30% dislike the Bush administration so much they 
want him impeached. If NSA were monitoring email 
and phone calls to identify pro-impeachment 
people, and if the accuracy rate were .90 and the 
error rate were .01, then the probability that 
people are pro-impeachment given that NSA 
surveillance system identified them as such, 
would be p=.98, which is coming close to 
certainty (p_1.00). Mass surveillance by NSA of 
all Americans' phone calls and emails would be 
very effective for domestic political intelligence.

But finding a few terrorists by mass surveillance 
of the phone calls and email messages of 300 
million Americans is mathematically impossible, and NSA certainly knows that.

Floyd Rudmin is Professor of Social & Community 
Psychology at the University of Tromsø in Norway. 
He can be reached at <mailto:frudmin at psyk.uit.no>frudmin at psyk.uit.no


The Freedom Archives
522 Valencia Street
San Francisco, CA 94110
(415) 863-9977
www.freedomarchives.org 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://freedomarchives.org/pipermail/news_freedomarchives.org/attachments/20060524/1cb242b3/attachment.htm>