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Why does $$-E \left(\frac{1}{2 \sigma^4}- \frac{(X-\mu)^2}{\sigma^6} \right) = \frac{1}{2 \sigma^4}$$

Shouldn't it be $-\frac{1}{2 \sigma^4}$? Note that $X \sim N(\mu, \sigma^2)$.

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    The minus sign in front turns the thing positive.2012-04-24
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    Or, as has been mis-attributed as a poem by W. H. Auden, "Minus times minus equals plus, The reason for this we need not discuss. "2012-04-24

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