##
Edgeworth's counts of dactyls in Virgil's Aeneid

### Description

Edgeworth (1885) took the first 75 lines in Book XI of
Virgil's *Aeneid* and classified each of the first four "feet" of the line
as a dactyl (one long syllable followed by two short ones) or not.

Grouping the lines in blocks of five gave a 4 x 25 table of counts,
represented here as a data frame with ordered factors, `Foot`

and
`Lines`

. Edgeworth used this table in what was among the first
examples of analysis of variance applied to a two-way
classification.

### Usage

data(Dactyl)

### Format

A data frame with 60 observations on the following 3 variables.

`Foot`

an ordered factor with levels `1`

< `2`

< `3`

< `4`

`Lines`

an ordered factor with levels `1:5`

< `6:10`

< `11:15`

< `16:20`

< `21:25`

< `26:30`

< `31:35`

< `36:40`

< `41:45`

< `46:50`

< `51:55`

< `56:60`

< `61:65`

< `66:70`

< `71:75`

`count`

number of dactyls

### Source

Stigler, S. (1999)
*Statistics on the Table*
Cambridge, MA: Harvard University Press, table 5.1.

### References

Edgeworth, F. Y. (1885).
On methods of ascertaining variations in the rate of births, deaths and marriages.
*Journal of the [Royal] Statistical Society*, 48, 628-649.

### Examples

data(Dactyl)
# display the basic table
xtabs(count ~ Foot+Lines, data=Dactyl)
# simple two-way anova
anova(dact.lm <- lm(count ~ Foot+Lines, data=Dactyl))
# plot the lm-quartet
op <- par(mfrow=c(2,2))
plot(dact.lm)
par(op)
# show table as a simple mosaicplot
mosaicplot(xtabs(count ~ Foot+Lines, data=Dactyl), shade=TRUE)