Letter to the Editor: Profiling: Not So Fast!

Profiling has caused great harm in our society, rightly sparking outrage against it. It’s a basic element of rage, rightly or wrongly held, against monuments to our past. But in dealing with it, dispassionate thought is necessary. What exactly is profiling? 

Two examples of bad: Some Black individuals smash windows and loot; therefore, all Black individuals smash windows and loot. Some white cops are racist; therefore, all white cops are racist. Clearly the logic is wrong, but when emotion overpowers logic, hateful profiling follows.

Two examples of good: A doctor uses a patient’s ethnic or racial background as a basis for diagnosis. A screening test for a disorder is based on a blood-sample profile.

Two different outcomes (Bayes’ Theorem): There’s a good screening test for your suspected illness with the probability of a true positive of 80 percent (a false negative of 20 percent) if you actually have the illness, and a true negative of 90 percent (a false positive of 10 percent) if you don’t. You test positive. Horrors! You’re 80 percent sure you have the illness. 

But not so fast! If the illness in the general population is 1 percent, your probability of having it is only 7.5 percent. On the other hand, with a population rate of 10 percent, your probability of having it rises to nearly 50 percent. Although the statement “A implies B” is not logically the same as “B implies A,” Bayes’ Theorem shows a connection that cannot be ignored.

Two choices: Try these practice numbers on the first two examples. Are we ready for real numbers? Can we overcome lack of quantifiable data and general misapplication in the use of the data? Can we risk either of the two types of error that may occur, each with serious consequences?

Two aspects of life: Profiling is unavoidable, but with matters of great importance, it must be done with great care. We know (or believe we know) what is from the past, and we must take a chance on what is or will be in the future. 

Stan Russell

Sturgeon Bay, Wisconsin