---
title: "Comparison of acfs"
output: html_document
---

## Comparison of artificial acfs

Consider the artificial series `x1` and `x2`:
```{r}
x1 <- c(39, 35, 16, 18, 7, 22, 13, 18, 20, 9, -12, -11, -19, -9, -2, 16)
x2 <- c(47, -26, 42, -10, 27, -8, 16, 6, -1, 25, 11, 1, 25, 7, -5, 3)
```

For each series:
- Plot the series.
- Make a scatter plot of the series and its lag 1 values (see p. 35 in Cowpertwait & Metcalfe).
- Plot the acf and comment.