faithful | R Documentation |

Waiting time between eruptions and the duration of the eruption for the Old Faithful geyser in Yellowstone National Park, Wyoming, USA.

`faithful`

A data frame with 272 observations on 2 variables.

[,1] | eruptions | numeric | Eruption time in mins |

[,2] | waiting | numeric | Waiting time to next eruption (in mins) |

A closer look at `faithful$eruptions`

reveals that these are
heavily rounded times originally in seconds, where multiples of 5 are
more frequent than expected under non-human measurement. For a
better version of the eruption times, see the example below.

There are many versions of this dataset around: Azzalini and Bowman (1990) use a more complete version.

W. Härdle.

Härdle, W. (1991).
*Smoothing Techniques with Implementation in S*.
New York: Springer.

Azzalini, A. and Bowman, A. W. (1990).
A look at some data on the Old Faithful geyser.
*Applied Statistics*, **39**, 357–365.
doi:10.2307/2347385.

`geyser`

in package MASS for the Azzalini–Bowman version.

```
require(stats); require(graphics)
f.tit <- "faithful data: Eruptions of Old Faithful"
ne60 <- round(e60 <- 60 * faithful$eruptions)
all.equal(e60, ne60) # relative diff. ~ 1/10000
table(zapsmall(abs(e60 - ne60))) # 0, 0.02 or 0.04
faithful$better.eruptions <- ne60 / 60
te <- table(ne60)
te[te >= 4] # (too) many multiples of 5 !
plot(names(te), te, type = "h", main = f.tit, xlab = "Eruption time (sec)")
plot(faithful[, -3], main = f.tit,
xlab = "Eruption time (min)",
ylab = "Waiting time to next eruption (min)")
lines(lowess(faithful$eruptions, faithful$waiting, f = 2/3, iter = 3),
col = "red")
```