# btmprobs: Fitted probabilities of the Terry-Bradley model In Rfast: A Collection of Efficient and Extremely Fast R Functions

 Fitted probabilities of the Terry-Bradley model R Documentation

## Fitted probabilities of the Terry-Bradley model

### Description

Fitted probabilities of the Terry-Bradley model.

### Usage

```btmprobs(x, tol = 1e-09)
```

### Arguments

 `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.

### Details

It fits a Bradley-Terry model to the given matrix and returns the fitted probabilities only.

### Value

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).

### Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@uoc.gr> and Manos Papadakis <papadakm95@gmail.com>.

### References

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.

``` g2tests, poisson.anova, anova, poisson_only, poisson.mle ```
```x <- matrix( rpois(10 * 10, 10), ncol = 10) ## not the best example though