R: Baseball Data from Agresti (2002)

baseball {BradleyTerry2} | R Documentation

## 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).

    ##  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)

[Package BradleyTerry2 version 1.0-6 Index]