predscor: Draws a predictions correlation plot, which visualizes the...

In classmap: Visualizing Classification Results

Draws a predictions correlation plot, which visualizes the correlations between the prediction terms in a regression fit.

Description

Computes the correlations between the prediction terms in a regression fit, and displays them graphically in a way that takes the standard deviations of the prediction terms into account. The input variables of the regression can be numerical, categorical, logical and character, and the regression model can be linear or generalized linear. The regression formula in lm or glm may contain transformations and interactions.

Usage

predscor(fit, maxnpreds = 8, sort.by.stdev = TRUE, adj.order = FALSE,
cell.length = "stdev", plot.abs.cor = FALSE, palette = NULL,
diagonalcolor = "black")

Arguments

fit	an output object of lm or glm.
maxnpreds	the maximal number of prediction terms to plot. When there are more prediction terms than this, those with smallest standard deviations are combined.
sort.by.stdev	if TRUE, sorts the prediction terms by decreasing standard deviation.
adj.order	if TRUE, this modifies the order of the prediction terms in an attempt to bring highly correlated prediction terms close to each other in the predscor display. If sort.by.stdev is TRUE, this happens after that sorting.
cell.length	if "stdev", the sides of the square cells on the diagonal of the correlation matrix are proportional to the standard deviation of their prediction term. If "sqrt" they are proportional to the square root of the standard deviation. If "equal" all sides are the same.
plot.abs.cor	if FALSE, the default, positive and negative correlations are shown in different colors, typically red and blue. If TRUE the absolute values of the correlations are shown.
palette	a vector with colors to display correlations ranging from -1 to 1. If NULL, the default palette shows positive correlations in red, negative correlations in blue, and uses white for correlation zero.
diagonalcolor	color of the cells on the diagonal of the correlation matrix. The default is "black".

Value

A list containing

cormat	the correlation matrix of the prediction terms.
predterms	matrix of cases by prediction terms.
predsummary	data frame with the standard deviation of each prediction term and the total linear prediction.

Author(s)

Rousseeuw, P.J.

References

Rousseeuw, P.J. (2025). Explainable Linear and Generalized Linear Models by the Predictions Plot https://arxiv.org/abs/2412.16980v2 (open access).

See Also

predsplot

Examples

data(data_titanic)
attach(data_titanic)
Pclass = factor(Pclass, unique(Pclass))
Sex = factor(Sex, labels = c("F","M"))
fit <- glm(y ~ Sex + Age + SibSp + Parch + Pclass, family=binomial)
predscor(fit)

# For more examples, we refer to the vignette:
## Not run: 
vignette("predsplot_examples")

## End(Not run)

classmap documentation built on April 29, 2026, 5:10 p.m.