BradleyTerry2 (version 1.1-2)

football: English Premier League Football Results 2008/9 to 2012/13

Description

The win/lose/draw results for five seasons of the English Premier League football results, from 2008/9 to 2012/13

Usage

football

Format

A data frame with 1881 observations on the following 4 variables.

season

a factor with levels 2008-9, 2009-10, 2010-11, 2011-12, 2012-13

home

a factor specifying the home team, with 29 levels Ars (Arsenal), ... , Wol (Wolverhampton)

away

a factor specifying the away team, with the same levels as home.

result

a numeric vector giving the result for the home team: 1 for a win, 0 for a draw, -1 for a loss.

Details

In each season, there are 20 teams, each of which plays one home game and one away game against all the other teams in the league. The results in 380 games per season.

References

Davidson, R. R. (1970). On extending the Bradley-Terry model to accommodate ties in paired comparison experiments. Journal of the American Statistical Association, 65, 317--328.

See Also

GenDavidson()

Examples

# NOT RUN {
### example requires gnm
if (require(gnm)) {
    ### convert to trinomial counts
    football.tri <- expandCategorical(football, "result", idvar = "match")
    head(football.tri)

    ### add variable to indicate whether team playing at home
    football.tri$at.home <- !logical(nrow(football.tri))

    ### fit Davidson model for ties
    ###  - subset to first and last season for illustration
    Davidson <- gnm(count ~
        GenDavidson(result == 1, result == 0, result == -1,
                    home:season, away:season,
                    home.adv = ~1, tie.max = ~1,
                    at.home1 = at.home, at.home2 = !at.home) - 1,
        eliminate = match, family = poisson, data = football.tri,
        subset = season %in% c("2008-9", "2012-13"))

    ### see ?GenDavidson for further analysis
}

# }