# Question: Suppose that we want to test the null hypothesis that

Suppose that we want to test the null hypothesis that an antipollution device for cars is effective.

(a) Explain under what conditions we would commit a type I error and under what conditions we would commit a type II error.

(b) Whether an error is a type I error or a type II error depends on how we formulate the null hypothesis. Rephrase the null hypothesis so that the type I error becomes a type II error, and vice versa.

(a) Explain under what conditions we would commit a type I error and under what conditions we would commit a type II error.

(b) Whether an error is a type I error or a type II error depends on how we formulate the null hypothesis. Rephrase the null hypothesis so that the type I error becomes a type II error, and vice versa.

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