Fitted probabilities of the Terry-Bradley model
Fitted probabilities of the Terry-Bradley model.
btmprobs(x, tol = 1e-09)
x |
A numerical square, usually not symmetric, matrix with discrete valued data. Each entry is a frequency, to give an example, the number of wins. x[i, j] is the number of wins of home team i against guest team j. x[j, i] is the number of wins of home team j against guest team i. |
tol |
The tolerance level to terminate the iterative algorithm. |
It fits a Bradley-Terry model to the given matrix and returns the fitted probabilities only.
A list including:
iters |
The numbetr of iterations required. |
probs |
A vector with probabilities which sum to 1. This is the probability of win for each item (or team in our hypothetical example). |
Michail Tsagris
R implementation and documentation: Michail Tsagris <mtsagris@yahoo.gr> and Manos Papadakis <papadakm95@gmail.com>.
Bradley R.A. and Terry M.E. (1952). Rank Analysis of Incomplete Block Designs: I. The Method of Paired Comparisons. Biometrika, 39(3/4):324-345.
Huang Tzu-Kuo, Ruby C. Weng and Chih-Jen Lin (2006). Generalized Bradley-Terry models and multi-class probability estimates. Journal of Machine Learning Research, 7:85-115.
Agresti A. (2002). Categorical Data Analysis (2nd ed). New York: Wiley.
x <- matrix( rpois(10 * 10, 10), ncol = 10) ## not the best example though res<-btmprobs(x)
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