null_model: Null model

In parsnip: A Common API to Modeling and Analysis Functions

Null model

Description

Fit a single mean or largest class model. null_model() is the user-facing function that relies on the underlying computational function, nullmodel().

Usage

null_model(mode = "classification", engine = "parsnip")

Arguments

mode	A single character string for the type of model. The only possible values for this model are "regression" and "classification".
engine	A single character string specifying what computational engine to use for fitting. Possible engines are listed below. The default for this model is "parsnip".

Details

null_model() defines a simple, non-informative model. It doesn't have any main arguments. This function can fit classification and regression models.

null_model() 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. When class probabilities are requested, the percentage of the training set samples with the most prevalent class is returned.

Engine Details

Engines may have pre-set default arguments when executing the model fit call. For this type of model, the template of the fit calls are below:

parsnip

null_model() |> 
  set_engine("parsnip") |> 
  set_mode("regression") |> 
  translate()

## Null Model Specification (regression)
## 
## Computational engine: parsnip 
## 
## Model fit template:
## parsnip::nullmodel(x = missing_arg(), y = missing_arg())

null_model() |> 
  set_engine("parsnip") |> 
  set_mode("classification") |> 
  translate()

## Null Model Specification (classification)
## 
## Computational engine: parsnip 
## 
## Model fit template:
## parsnip::nullmodel(x = missing_arg(), y = missing_arg())

Prediction types

parsnip:::get_from_env("null_model_predict") |>
  dplyr::select(mode, type)

## # A tibble: 5 x 2
##   mode           type   
##   <chr>          <chr>  
## 1 regression     numeric
## 2 regression     raw    
## 3 classification class  
## 4 classification prob   
## 5 classification raw

See Also

fit.model_spec()

Examples

null_model(mode = "regression")

parsnip documentation built on Jan. 11, 2026, 9:06 a.m.