Log score for nominal outcomes

Log score for nominal outcomes

The Log Score is the negative logarithm of the probability assigned to the observed value. It is a proper scoring rule. Small values are better (best is zero, worst is infinity).

Usage

logs_nominal(observed, predicted, predicted_label)

Arguments

observed

A factor of length n with N levels holding the observed values.

predicted

nxN matrix of predictive probabilities, n (number of rows) being the number of observations and N (number of columns) the number of possible outcomes.

predicted_label

A factor of length N, denoting the outcome that the probabilities in predicted correspond to.

Value

A numeric vector of size n with log scores

Input format

Overview of required input format for nominal forecasts

See also

Other log score functions: logs_sample(), scoring-functions-binary

Examples

factor_levels <- c("one", "two", "three")
predicted_label <- factor(c("one", "two", "three"), levels = factor_levels)
observed <- factor(c("one", "three", "two"), levels = factor_levels)
predicted <- matrix(c(0.8, 0.1, 0.4,
                      0.1, 0.2, 0.4,
                      0.1, 0.7, 0.2),
                    nrow = 3)
logs_nominal(observed, predicted, predicted_label)
#> [1] 0.2231436 0.3566749 0.9162907