ROBERTS What did you think of The Black Swan on the same topic?
MLODINOW Itâ€™s on the topic of how little things can cause big changes, you mean, and . . .
ROBERTS And how poorly we understand what really matters.
MLODINOWÂ I haven’t read the book from beginning to end so itâ€™s hard to comment on that.
ROBERTS What about his previous book? There are similar ideas in the two books.
MLODINOW I didnâ€™t really notice that book when I started writing Drunkardâ€™s Walk; I wasnâ€™t aware of the book. I had looked–in the library–gone through tons of books that seemed somehow related to randomness and somehow that one didnâ€™t stand out to me. Sometime later it came out in paperback and it got very popular. Then I rediscovered it, and yes, I agree with a lot of what he says in that first book, but I still never read it from cover to cover. Iâ€™m not the type who feels compulsive about reading everything thatâ€™s been written on the subject that Iâ€™m writing on.
ROBERTS Yes. I always think of his book as being about these very long-tailed distributions–not only about that, but they play a large role–whereas you didnâ€™t mention long-tailed distributions in your book.
MLODINOW Not explicitly, but I did talk about that idea and certainly the idea that not everything follows a normal distribution and how important it is to note that, for instance in Hollywood–Hollywood box office receipts. But I think The Black Swan was exclusively about that, so in that sense it was a different topic.
[For readers who donâ€™t know what that is, if youâ€™re talking about the probability of events occurring–letâ€™s say youâ€™re talking about the probability of a movie making a certain amount of money–there may be a mean amount of money that a movie makes or that a movie of that type makes. Then there will be fluctuations around it; some movies will make more, some movies will make less. The normal distribution is a distribution of the revenues that would follow a bell curve and the long-tailed distribution differs. One of the important respects that it differs in is that it has a lot more results that are far from the average that you would expect in a normal distribution. So if the average movie makes $1,000,000 or to be more realistic letâ€™s say the average movie makes $50,000,000 and if it was normally distributed you would have, depending on the variance, but letâ€™s just say you would have a certain number that make 40 or would make 60 and another small number would make 30 or 70 and you have a very small number indeed–probably practically zero–that would make $500,000,000. In Hollywood the way it really works is there are more that differ that far from the median than you would have if it were a normal distribution. Thatâ€™s what they call a long-tailed distribution–the number of occurrences that are far from the average is much higher than you would expect with the normal distribution. — LM]
So that applies in many areas of life as well. I think that translated into what we were just talking about, it means that these little minor incidents can have major effects on you. Itâ€™s not all kind of pushed toward the mean effect, which is just going into my office and doing more physics.
ROBERTS Yes, I think that if you take the different things that have happened to you and you measured their effect, the effects will have a power-law distribution. A tiny number will have a huge effect and . . .