I'm trying to typeset an equation that contains the following:

```
\begin{align*}
\hat{\E[(R_{i}-\hat R_{i})^{2}]}
\end{align*}
```

However, this is what I get

Is this a bug? Is there any way around it? I'd like the "hat" to be over the whole expression, not just the expectation operator which I've defined as:

```
\newcommand{\E}{\mathbb{E}}
```

## Best Answer

You have to use

or if you want a bigger hat see this question.