Waiting for a decreasing run to break
Question
Let be i.i.d. draws from a continuous distribution. Define as the first index at which the sequence goes up, i.e. and . Compute .
Short answer
. means the first values are in decreasing order, which has probability since all orderings are equally likely. Summing tail probabilities, , so the log is .
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Open the worked solutionLessons behind this question
- Expectation, Mean, and Variance
- Conditional Expectation and Variance Revisited
- Continuous Random Variables and Probability Density Functions
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