This is a mini lecture on hindsight bias. Looking back, it all seems so clear.
Hindsight bias is the inclination to see events that have already occurred as
being more predictable than they were before they took place. In other words,
after an event occurs we tend to look back on that event as being something
that we should have seen coming, or in fact did see coming, and hindsight bias
often occurs when you learn something new in a class. Maybe learning it was
difficult, but after you learn it you think that anyone else should be able to
learn it easily, or perhaps that everyone else already knows it or as Dr. Watson
said to Sherlock Holmes, anything seems commonplace once explained. Hindsight
bias is captured in the exclamation, "I knew it all along!" At a wedding, someone
looks at the happy couple and says "Yeah, I knew from the moment I first saw them
together that they were going to get married" unless of course they break up,
and then the same person says "you know I had my doubts about them from the start".
If you are unfortunate enough to have been a political leader when something
has gone horribly wrong, you will likely be the victim of others hindsight bias.
After the fact someone will say they should have known. That is what was said
of Admiral Husband Kimmel after the Japanese surprise attack on Pearl Harbor
in 1941. He should have seen it coming, all of the signs were there, how could he
have missed them? And so he was relieved of his command by Admiral Chester Nimitz.
After the space shuttle Challenger explosion in 1986, many critics suggested
that NASA should have known that it was too cold to launch that day. George W.
Bush was criticized for FEMA's slow response to the flooding of New Orleans
after Hurricane Katrina, because he should have known that that flooding
would occur, and after the attacks of 9/11 it was pointed out that the FBI had
warned the president that Osama bin Laden was determined to strike in the
United States. He should have seen it coming.
But are those criticisms entirely fair? Was it really that easy to have seen it
coming? It is easy to look back after an event occurs with perfect 20/20
hindsight, and then find all of the clues leading up to the event. Even Admiral
Nimitz who replaced Admiral Kimmel after Pearl Harbor, said of his old friend, it
could have happened to anybody. No one else would have seen it coming
either. So let's see if you too can be a victim of hindsight bias. I am going to
teach you something unrelated to statistics, and then see if you
understand the concept, and then I'm going to test you on it. Now this is an
example that I learned from Dr. Eric Mazur from Harvard when he visited
our University to talk about learning. His concept is from the field of physics
and it states, "molecules expand when heated" this is why you would not want to
lay railroad tracks in the winter, because in the summer heat, the rails
will expand and buckle the rails, and this is why you see expansion joints in
bridges. In the summer, the whole metal bridge expands and it closes the joints.
In the winter, the bridge shrinks slightly and the gaps open. So when we
have molecules that are cold, they are close together, but when they're heated
they expand. When they cool down they get closer together but you heat them back
up again they expand. Cold, hot, cold, hot. Any questions? Do you understand this
concept? Do you understand it well enough that
you can apply it? Okay let's try. Here we have a one inch steel plate with a
circle cut in the center. We are going to heat it up. My question for you is when
we heat it will the circle get larger? Will the circle gets smaller? Or, will the
circle stay the same size? Take what you know about molecules and heat and answer
that question. Do you have it? Do you think you know the answer?
Share your answer with someone near you. The correct answer is that the entire
plate will expand and the circle will get larger. This might help to explain it.
Simplify the problem. Strip away everything but the ring of molecules
inside the circle. Imagine that there are 10 of us standing in a circle holding
hands. We are all molecules. We get heated up. So what are we going to have to do to
expand? What will we have to do to be further from each other?
What will that do to our circle? It will get bigger. The whole metal plate will
get bigger. When I do this example in class, everyone says I understand the
concept, but I'm amazed at how many people get it wrong. Now of course maybe
I'm a little deceived by hindsight bias myself, because the first time I was
shown the example I got it wrong. But now that it has been explained, it was
obvious all along. Looking back, it all seems so clear. So what does this have to
do with statistics? As you are learning statistics, we will learn lots of new
material. You are very likely to hear something once or watch me do an example
and think "well that looks easy. I understand that". But later on, I
hear students say "it was really easy when we did it in class, but then when I
got to the homework, I forgot everything!" it's not that you forgot it, you did not
really learn it. You overestimated how much you understood! Looking back at the
example, it seems easier than it was. So in the statistics class, be skeptical of
your own understanding. Assume that you understand less than you do, and then ask
questions for clarification. Don't assume that hearing something once or reading
it once is enough for you to learn it. Spend a little time every day reviewing
what you are learning, because it is normal to think that you understand and
then find out that you overestimated your understanding. Hindsight bias
happens to all of us. It will happen to you and your best defense against
hindsight bias is to never assume that you know something the first time, and
spend plenty of time reading, listening, and reviewing what you've learned in
this course.