baseball {BradleyTerry2}

Baseball Data from Agresti (2002)

Description

Baseball results for games in the 1987 season between 7 teams in the Eastern Division of the American League.

Usage

baseball

Format

A data frame with 42 observations on the following 4 variables.

home.team

a factor with levels Baltimore, Boston, Cleveland, Detroit, Milwaukee, ⁠New York⁠, Toronto.

away.team

a factor with levels Baltimore, Boston, Cleveland, Detroit, Milwaukee, ⁠New York⁠, Toronto.

home.wins

a numeric vector.

away.wins

a numeric vector.

Note

This dataset is in a simpler format than the one described in Firth (2005).

Source

Page 438 of Agresti, A. (2002) Categorical Data Analysis (2nd Edn.). New York: Wiley.

References

Firth, D. (2005) Bradley-Terry models in R. Journal of Statistical Software, 12(1), 1–12.

Turner, H. and Firth, D. (2012) Bradley-Terry models in R: The BradleyTerry2 package. Journal of Statistical Software, 48(9), 1–21.

See Also

BTm()

Examples

##  This reproduces the analysis in Sec 10.6 of Agresti (2002).
data(baseball) # start with baseball data as provided by package

##  Simple Bradley-Terry model, ignoring home advantage:
baseballModel1 <- BTm(cbind(home.wins, away.wins), home.team, away.team,
                      data = baseball, id = "team")

##  Now incorporate the "home advantage" effect
baseball$home.team <- data.frame(team = baseball$home.team, at.home = 1)
baseball$away.team <- data.frame(team = baseball$away.team, at.home = 0)
baseballModel2 <- update(baseballModel1, formula = ~ team + at.home)

##  Compare the fit of these two models:
anova(baseballModel1, baseballModel2)