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Edgeworth's counts of dactyls in Virgil's Aeneid

Dactyl.Rd

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)
#>     Lines
#> Foot 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
#>    1   3    3     5     5     4     4     2     2     2     1     2     4     3
#>    2   1    4     0     3     3     3     5     2     2     4     3     1     2
#>    3   1    2     4     2     5     2     1     2     2     2     0     2     2
#>    4   2    2     1     0     3     1     2     0     2     1     1     2     1
#>     Lines
#> Foot 66:70 71:75
#>    1     2     4
#>    2     3     2
#>    3     0     1
#>    4     1     0

# simple two-way anova
anova(dact.lm <- lm(count ~ Foot+Lines, data=Dactyl))
#> Analysis of Variance Table
#> 
#> Response: count
#>           Df Sum Sq Mean Sq F value    Pr(>F)    
#> Foot       3 27.650  9.2167  6.5499 0.0009826 ***
#> Lines     14 20.233  1.4452  1.0271 0.4467408    
#> Residuals 42 59.100  1.4071                      
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

# 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)