# David John Aldous

David John Aldous
(University of California, Berkeley)

#### Title: Examples of Probability in the Real World

A first undergraduate course in Probability gives a rather limited view of real world uncertainty. At Berkeley I developed a second course, intended to illustrate the breadth of contexts where probabilities arise, rather than developing mathematical technique. I will describe a few such topics.

1. Can we tell if person $A$ is better than person $B$ at estimating unknowable probabilities of unique near-future events (answer: Yes); and is the winner of such a multi-player “prediction tournament” likely to be the best estimator (answer: No).
2. At the end of a long line at airport security, how long do you stand still until a wave of motion reaches you?
3. What is the cost of an error in estimating probabilities, outside the “rare event with huge consequences” context?
4. In any long-running competition with one winner to be found amongst many contestants, why do we know roughly how many contestants will ever have a serious (>25%, say) chance of winning?
5. How can we quickly estimate the chance Netherlands beats France in a hypothetical football game tomorrow, and how accurate is that estimate likely to be?