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IncludeConstantBasis

is an option for LinearModelFit and other fitting functions that specifies whether a constant term should be included if not explicitly given in the list of basis functions.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
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History
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IncludeConstantBasis

IncludeConstantBasis

is an option for LinearModelFit and other fitting functions that specifies whether a constant term should be included if not explicitly given in the list of basis functions.

Details

  • The default setting IncludeConstantBasis->True adds a constant basis to the model if one is not specified in the list of basis functions.
  • Linear and generalized linear models typically compare the fitted model to the mean response model, which contains only a constant basis function.
  • Setting IncludeConstantBasis->False can be used to fit models without a constant basis function.

Examples

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Basic Examples  (1)

Fit a simple linear regression model:

Wolfram Language code: data = {{0, 1}, {1, 0}, {3, 2}, {5, 4}};
Wolfram Language code: LinearModelFit[data, x, x]

Fit the linear model with intercept zero:

Wolfram Language code: LinearModelFit[data, x, x, IncludeConstantBasis -> False]

Scope  (2)

Fit a generalized linear model:

Wolfram Language code: data = {{1, 1}, {2, .5}, {3, 2}, {5, 6}};
Wolfram Language code: GeneralizedLinearModelFit[data, x, x, ExponentialFamily -> "Gamma"]//Normal

Fit the model without a constant term in the linear predictor:

Wolfram Language code: GeneralizedLinearModelFit[data, x, x, ExponentialFamily -> "Gamma", IncludeConstantBasis -> False]//Normal

Fit logit models with and without a constant term:

Wolfram Language code: LogitModelFit[{.1, .3, .5, .6, .8}, x, x]//Normal
Wolfram Language code: LogitModelFit[{.1, .3, .5, .6, .8}, x, x, IncludeConstantBasis -> False]//Normal

Probit models:

Wolfram Language code: ProbitModelFit[{.1, .3, .5, .6, .8}, x, x]//Normal
Wolfram Language code: ProbitModelFit[{.1, .3, .5, .6, .8}, x, x, IncludeConstantBasis -> False]//Normal
Wolfram Research (2008), IncludeConstantBasis, Wolfram Language function, https://reference.wolfram.com/language/ref/IncludeConstantBasis.html.

Text

Wolfram Research (2008), IncludeConstantBasis, Wolfram Language function, https://reference.wolfram.com/language/ref/IncludeConstantBasis.html.

CMS

Wolfram Language. 2008. "IncludeConstantBasis." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/IncludeConstantBasis.html.

APA

Wolfram Language. (2008). IncludeConstantBasis. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/IncludeConstantBasis.html

BibTeX

@misc{reference.wolfram_2026_includeconstantbasis, author="Wolfram Research", title="{IncludeConstantBasis}", year="2008", howpublished="\url{https://reference.wolfram.com/language/ref/IncludeConstantBasis.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_includeconstantbasis, organization={Wolfram Research}, title={IncludeConstantBasis}, year={2008}, url={https://reference.wolfram.com/language/ref/IncludeConstantBasis.html}, note=[Accessed: 13-June-2026]}