Dactyl | R Documentation |
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.
data(Dactyl)
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
Stigler, S. (1999) Statistics on the Table Cambridge, MA: Harvard University Press, table 5.1.
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.
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)
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