= A p-value does not determine the type II error probability
{title2=$\beta(\delta)=\Phi(c-\delta)-\Phi(-c-\delta)$}
Consider a two-sided test rejecting when $|Z|>c$, with $Z$ having a <normal distribution> of mean $\delta$ and variance one. Here $\Phi$ is the <cumulative distribution function> of the <standard normal distribution>. Under a nonzero alternative $\delta$, the <type II error> probability is the displayed function. It tends to the nonrejection probability under the null as $\delta\to0$, and to zero as $\delta\to+\infty$. A particular observed $Z=z$ has positive density under all these alternatives. Its null-calibrated <p-value> therefore does not select one value of $\beta$. The <power function> describes repeated-sampling performance at specified alternatives.
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