calculate_pi_ratings {piratings}

Calculate Pi Ratings

Description

This function calculates dynamic performance ratings called "pi ratings" for sport teams in competitive matches. The pi rating system was developed by Constantinou and Fenton (2013) <doi:10.1515/jqas-2012-0036>

Usage

calculate_pi_ratings(teams, outcomes, lambda, gamma, b, c, return_e)

Arguments

teams

an (n x 2) character matrix, contains unique names for the respective home and away teams in n subsequent matches

outcomes

an (n x 2) numeric matrix, contains the points that the respective home and away teams scored in n subsequent matches

lambda

a constant, the learning rate for performance from recent matches, default value: 0.035

gamma

a constant, the learning rate for performance from home to away and vice versa, default value: 0.7

b

a constant, logarithmic base, default value: 10

c

a constant, default value: 3

return_e

a boolean variable, conditions the function to return either the mean squared error when return_e = TRUE, or the pi ratings when return_e = FALSE, default value: FALSE

Value

either an (n x 2) matrix containing the pi ratings for the teams in the n input matches or the mean squared error for the specific parameter setting, conditional on boolean parameter return_e being FALSE or TRUE

Examples

# toy example
teams <- matrix(c("team A", "team B", "team B", "team A"), nrow = 2)
outcomes <- matrix(c(1, 3, 2, 1), nrow = 2)
calculate_pi_ratings(teams, outcomes)