Question
Consider a random sample of size $n$ from a normal population with mean $\mu$ and variance $\sigma^{2}$, both unknown. Derive the MLE of $\sigma$.
Step 1
The likelihood function is given by: \[ L(\mu, \sigma^2 | y) = \prod_{i=1}^{n} \frac{1}{\sqrt{2\pi\sigma^2}} e^{-\frac{(y_i - \mu)^2}{2\sigma^2}} \] Show more…
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Consistency
Consider two estimators of $\sigma^{2}$ for a sample $x_{1}, x_{2}, \ldots, x_{n},$ which is drawn from a normal distribution with mean $\mu$ and variance $\sigma^{2}$. The estimators are the unbiased estimator $s^{2}=\frac{1}{n-1} \sum_{i=1}^{n}\left(x_{i}-\bar{x}\right)^{2}$ and the maximum likelihood estimator $\hat{\sigma}^{2}=\frac{1}{n} \sum_{i=1}^{n}\left(x_{i}-\bar{x}\right)^{2}$ Discuss the variance properties of these two estimators.
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