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The Chernoff bound on a standard normal random variableZgivesP{Z>a}≤e-a2/2,a>0. Show, by considering the densityZ, that the right side of the inequality can be reduced by the factor2. That is, show that

P{Z>a}≤12e-a2/2a>0

Short Answer

Expert verified

Therefore,

P{Z>a}=∫a∞12Ï€e-x22dux==¯-a∫0∞12Ï€e-(x+)22dx=∫0∞12Ï€e-x2+3ax+a22dx=eu222π∫0∞e-x22e-axÁåŸâ‰¤1dx≤eÏ€222π∫0∞e-x22dxÁåŸ=Ï€/2=12e-a22,a>0

Step by step solution

01

Given Information.

The Chernoff bound on a standard normal random variableZ givesP{Z>a}≤e-a2/2,a>0.

02

Explanation.

Let Zbe a standard normal random variable. Assume thata>0. Using the definition of the standard normal density function, we have that

P{Z>a}=∫a∞12Ï€e-y22dux=u-a=∫0∞12Ï€e-(x+Δ)22dx=∫0∞12Ï€e-x2+2ux+a22dx=eÏ€222π∫0∞e-z22e-axÁåŸâ‰¤1dx≤ez222π∫0∞e-z22dxÁåŸ=Ï€/2=12e-Ï€22.

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Most popular questions from this chapter

Each of the batteries in a collection of 40batteries is equally likely to be either a type A or a type B battery. Type A batteries last for an amount of time that has a mean of 50and a standard deviation of 15; type B batteries last for a mean of 30and a standard deviation of 6.

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Assuming that the random variables Xi,i≥1,are independent, determine r.

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