Wednesday, June 16, 2010

Why We Get Tricked Into Lying With Statistics: Conditional Probability, Ecotpic Pregnancy, and Confirmation Bias

Calling All Statisticians!

Please, somebody, HELP me figure out the probability of a live birth from a non-tubal ectopic pregnancy.

In the next couple of posts, I hope to explain briefly just why people fall into the trap of “lying with statistics” as one of the trappings of our humanity as we try to understand truth and the nature of things. I think the matter of figuring out the true probability of delivering a live birth from a non-tubal ectopic pregnancy can not only give the reader a glimpse into the science of understanding behavior (some areas of psychology and health depend and revolve around science and factual truth), but it can teach us something about “confirmation bias” or seeing only what we want to see in the world or a situation.

As a Christian, we should seek truth in the Word of God and in our world, both in terms of relationships and in terms of the wisdom with which we conduct ourselves. Using math to test the truth of the ideas that we have about “the way things are” or how we understand the world can be invaluable. I’d like to expand upon the errors I see in the misuse (or the honest yet ignorant use) of numbers and probability to mislead people in this current discussion of ectopic pregnancy. To do that, I am going to have to give some examples, but I ultimately want to put out a call to statisticians to help me rightly discern how significant the numbers are to the Christian who wants to know the truth and wisdom in this area. I hope to frame out the problem, but in so doing, I think that the reader here will develop a deeper appreciation for the fact that:
Life is not always as simple as we’d like it to be.

I would like the reader to understand my concerns about how statistics have been used in this discussion, perhaps innocently though in a misleading way. I believe that this insight can give us a new window of insight into our own motives and how we think about things. I hope that this discussion brings the reader two big payoffs: (1.) we’ll figure out how common non-tubal ectopic live births really prove to be, and (2.) we can learn how to look more thoughtfully at the world from a broader perspective in a way that will ultimately help us resist undue influence and surreptitious manipulation. I am going to need some expert help in this area, but I can at least get us started by explaining how such matters can be framed and should be framed out in terms of statistics. In other words, I hope to show you how complicated life can be. (But that’s a good thing, because some things in life are very complicated.) Let’s take it a step at a time.

A Little Example of Innocent “Lying with Statistics”

A classic example from Darrell Huff’s “How to Lie with Statistics” (1954) pops into my head as a simple explanation of confirmation bias, wishful thinking, or seeing only what we want to see.  Though it does discuss some math here and there, the book makes for good reading for anyone who wants to understand how numbers and such can influence us.  In other words, it is not a math text but a discussion of how people can use math (or misuse it).  It's down to earth and presents the topic in a manner that's quite palatable if you haven't thought about setting up a math problem in a number of  years!  (I don't know why I never thought to put it in my suggested reading list, and I should.)

Speaking of psychologists…

Imagine that a psychologist that you run into at the gym twice a week says, “I am really starting to believe most people in society today are psychotic!” They well could be, if we all inhaled some toxic fumes from a local pharmaceutical plant. But what else could it be? Well lets say that Dr. Psyche, PhD spent ten years working as a career counselor in an affluent area and at a facility with lots of resources, with clients who were very advanced ($). He then goes back to school to specialize in mental illness and starts a practice in a psychiatrist’s office with a general focus (not a specialist in ADD or pain or OT). He just happens to get assigned schizophrenics, some narcissists, a borderline, and one patient with chronic pain. 80% of his patient load display psychotic symptoms, and these same patients have remained in his care for more than a year. Discussions in his office among his healthcare team involve the discussion of management of psychotic symptoms, and his continuing education interests all pertain to psychosis.

Do you see the potential problem here? His input is not balanced in terms of all possible subjects in life but is geared to psychosis, even within his profession. Most of the people he interacts with have psychotic features, and Lord knows the functional ability of his coworkers. (Psychologists can be just as unbalanced as everyone else can be.) And he went from an area of practice where people were more of a general sample of the general population, but actually, the subset of people that he worked with were higher functioning and had means. So the socio economic status of his previous clientele actually became another variable, and this pool of people was not truly a general sample of all people. Most everybody in our friend Mr. Psyche’s world is psychotic, the right side of his brain is especially attuned to look for indicators of psychosis, so it is true of his IMPRESSION that “everyone” is psychotic.

Seeing What We Want to See and the Limits of Our Field of Vision

It is easy to understand all the world as limited to only the group of people with which we interact, and we are wrong to do this. If you never saw someone wear a neck tie before, and you never saw a tie in your culture, it might never occur to you that ties exist. But on the other side of the globe, everyone could wear them. You would be wrong to say that no one anywhere wears ties.

Concerning the issue of ectopic pregnancy rates and their meaning, I’m auspicious because we do have numbers that we can use to arrive at some reasonable conclusions. We still have to consider the caveat of where we get our information and how reliable it truly proves to be, but we can get more specific. I would like to take you on a short journey into statistics land, enough to appreciate the general landscape. I at least know my way around a little and who/when/how to call for help when I am out of my element. And I hope that a reader here will either lend some assistance or will direct me to someone who can help us rightly discern the truth.

As I’ve said many times before, the truly miraculous thing about our brains and our minds is not our ability to realize truth. Our natural ability and tendency as human beings to run and hide from unpleasant truth or experiences often FAR outweigh our tendency to gravitate to things that are easy and pleasant. Duty and self-control require effort, and we tend to follow the path of least resistance and ease, just because we are human. If we understand this tendency, It helps us see truth more clearly. It helps us find wisdom and prevents us from double-minded windy ways of scattered thinking. And we learn to see the manipulator coming toward us (so we can see trouble coming, taking measures to avoid falling into traps).

Stay tuned.