caret (version 4.42)

nullModel: Fit a simple, non-informative model

Description

Fit a single mean or largest class model

Usage

nullModel(x, ...)
## S3 method for class 'default':
nullModel(x = NULL, y, ...)
## S3 method for class 'nullModel':
predict(object, newdata = NULL, ...)

Arguments

x

An optional matrix or data frame of predictors. These values are not used in the model fit

y

A numeric vector (for regression) or factor (for classification) of outcomes

...

Optional arguments (not yet used)

object

An object of class nullModel

newdata

A matrix or data frame of predictors (only used to determine the number of predictions to return)

Value

• The output of nullModel is a list of class nullModel with elements
• call
  the function call
• value
  the mean of y or the most prevalent class
• levels
  when y is a factor, a vector of levels. NULL otherwise
• n
  the number of elements in y
• predict.nullModel returns a either a factor or numeric vector depending on the class of y. All predictions are always the same.

Details

nullModel emulates other model building functions, but returns the simplest model possible given a training set: a single mean for numeric outcomes and the most prevalent class for factor outcomes.

Examples

outcome <- factor(
                  sample(letters[1:2], 
                         size = 100, 
                         prob = c(.1, .9), 
                         replace = TRUE))
useless <- nullModel(y = outcome)
useless
predict(useless, matrix(NA, nrow = 10))