Tucker's Reviews > The Drunkard's Walk: How Randomness Rules Our Lives

The Drunkard's Walk by Leonard Mlodinow
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's review
Dec 25, 2009

really liked it
bookshelves: finished, brain
Read in September, 2009

Mlodinow presents two definitions of randomness: the "frequency interpretation," identified by Charles Sanders Peirce in 1896 as a method that will produce one set as frequently as any other set, and the "subjective interpretation," based on our inability to predict results. (pp. 84-85) Falling under the subjective category is research dating back to the 1930s that showed that "people could neither make up a sequence of numbers that passed mathematical tests for randomness nor recognize reliably whether a given string was randomly generated." (p. ix)

Unlike Nassim Nicholas Taleb in The Black Swan, Mlodinow has more use for the idea of the bell curve in describing overall expectations. However, he points out that it is impossible to draw the bell curve from a single data point, which is often all that we have. He writes: "When we observe a success or a failure, we are observing one data point, a sample from under the bell curve that represents the potentialities that previously existed. We cannot know whether our single observation represents the mean or an outlier, an event to bet on or a rare happening that is not likely to be reproduced." (p. 142)

His book uses many examples from sports, such as the fact that firing a coach after a bad season doesn't correlate with improved team performance, although popular belief holds the coach responsible. These concepts were presented well and it was enjoyable to try to work through the math.


"The theory of randomness is fundamentally a codification of common sense. But it is also a field of subtlety, a field in which great experts have been famously wrong and expert gamblers infamously correct. What it takes to understand randomness and overcome our misconceptions is both experience and a lot of careful thinking." (p. 21)

"We associate randomness with disorder. Yet although the lives of 200 million drivers vary unforeseeably, in the aggregate their behavior could hardly have proved more orderly. ... But it was not just the regularities that astonished them [the 19th-century scientists:]. It was also the nature of the variation. Social data, they discovered, often follow the normal distribution." (p. 148)
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