Drug-detecting rats? Dogs are big and expensive. Rats are small and cheap.Might rats be

Chapter 0, Problem 20.10

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Drug-detecting rats? Dogs are big and expensive. Rats are small and cheap.Might rats be trained to replace dogs in sniffing out illegal drugs? A first study ofthis idea trained rats to rear up on their hind legs when they smelled simulatedcocaine. To see how well rats performed after training, they were let loose on asurface with many cups sunk in it, one of which contained simulated cocaine. Fourout of six trained rats succeeded in 80 out of 80 trials.9 How should we estimatethe long-term success rate p of a rat that succeeds in every one of 80 trials?(a) What is the rats sample proportion p? What is the large-sample 95%confidence interval for p? Its not plausible that the rat will always be successful,as this interval says.(b) Find the plus four estimate p and the plus four 95% confidence interval for p.These results are more reasonable. This example illustrates how p improves on pwhen a sample has almost all successes or almost all failures.