common-mistakes.qmd

# Common Mistakes

---

{{< include shared-config.qmd >}}

## Parameters versus random variables

The parameters of a probability distribution shouldn't involve the random variables being modeled:

:::{.callout-warning}

### This is wrong

$$X \sim Pois(\lambda)$$
$$\hat{\lambda}_{ML} \rightarrow_D N(\bar{X}, \lambda/n)$$
:::

::::{.solution}
$$\hat{\lambda}_{ML} \rightarrow_D N(\lambda, \lambda/n)$$
::::



Expectations are means, not sums, despite the similarity of $\Sigma$ and $\text{E}$.
Really, we should use $\mu$ instead of $\text{E}$.

## R

### Don't copy-paste code

Successful programmers don't use copy-paste! [Write functions instead.](https://r4ds.hadley.nz/functions#introduction)

## Quarto

### Separate divs and slide breaks

Make sure not to put a div `:::` on the next line after a slide break `---`:

```
---
::: notes
:::
```

There needs to be an empty line between them:

```
---

::: notes
:::
```

### `library(printr)` currently breaks `df-print: paged`

See <https://github.com/yihui/printr/issues/41>

## LaTeX

Double superscript issues: <https://www.overleaf.com/learn/latex/Errors/Double_superscript>