Are you an expert? Take the test and find out

A sidebar to Ian Ayres's August 31, 2007 Financial Times story headlined "How computers killed the expert" offered a test entitled "Are you an expert?"

It follows.

Are you an expert?

The human mind tends to suffer from a number of well-documented cognitive failings and biases that distort our ability to predict accurately. We tend to give too much weight to unusual events that seem salient. And once we form a mistaken belief about something, we tend to cling to it. As new evidence arrives, we’re likely to discount contrary evidence and focus instead on evidence that supports our pre-existing beliefs.

In fact, it’s possible to test your own ability to make unbiased estimates. For each of the following 10 questions, give the range of answers that you are 90 per cent confident contains the correct answer. For example, for the first question, you are supposed to fill in the blanks: "I am 90 per cent confident that Martin Luther King’s age at the time of his death was somewhere between ___ years and ___ years." Don’t worry about not knowing the exact answer — and no using Google.


1. What was Martin Luther King Jr.'s age at death? Low __ High __

2. What is the length of the Nile river, in miles? Low __ High __

3. How many countries belong to OPEC? Low __ High __

4. How many books are there in the Old Testament? Low __ High __

5. What is the diameter of the moon, in miles? Low __ High __

6. What is the weight of an empty Boeing 747, in lbs? Low __ High __

7. In what year was Wolfgang Mozart born? Low __ High __

8. What is the gestation period of an Asian elephant, in days? Low __ High __

9. What is the air distance from London to Tokyo, in miles? Low __ High __

10. What is the deepest known point in the ocean, in feet? Low __ High __


Answering "I have no idea" is not allowed. It’s also a lie. Of course you have some idea. You know that the deepest point in the ocean is more than 2in and less than 100,000 miles. The correct answers are given at the end of this article — so you can check to see how many you got right. You can’t win if you don’t play. If all 10 of your intervals include the correct answer, you’re underconfident. Any of us could have made sure that this occurred — just by making our answers arbitrarily wide. I’m 100 per cent sure Mozart was born sometime between 33BC and say, 1980. But almost everyone who answers these questions has the opposite problem, one of overconfidence — they can’t help themselves from reporting ranges that are too small. People think they know more than they actually know. In fact, when academics Ed Russo and Paul Schoemaker tested more than 1,000 people, they found that most people missed between four and seven of the questions. Fewer than 1 per cent of the people gave ranges that included the right answer nine or 10 times. Ninety-nine per cent of people were overconfident.


The answers:

1. 39 years

2. 4,187 miles

3. 13 countries

4. 39 books

5. 2,160 miles

6. 390,000 lbs.

7. 1756

8. 645 days

9. 5,959 miles

10. 36,198 feet