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Negative log-likelihood

As explained in Causal AI

The negative log-likelihood loss function is the negative logarithm of the likelihood and is minimized to estimate parameters.

Negative log-likelihood is a loss function equal to the negative logarithm of a model’s likelihood. Minimizing it estimates parameters just as maximizing likelihood or log-likelihood does, while fitting naturally into machine-learning optimization workflows. section 2.3.4

Its practical role follows from how parameter estimation is performed:

  • Use numerical optimization when no closed-form maximum-likelihood solution is available. section 2.3.4
  • Fit neural-network parameters by seeking a candidate with relatively high likelihood, expressed as low negative log-likelihood. section 2.3.4
  • Add regularization when optimization should discourage extreme parameter values; L2 regularization penalizes the sum of squared parameters. section 2.3.4

How Causal AI covers it

How deep it goes
Defines the likelihood transformation and optimization role, then connects it to numerical optimization and regularization.
Examples
Uses linear regression, neural networks, and L2 regularization as estimation and optimization examples.
What it assumes
Assumes likelihood-based parameter estimation and distinguishes point estimation from Bayesian estimation.
What you can do after
Apply it via numerical optimization to estimate parameters when likelihood maximization lacks a closed-form solution.
How it connects
Connects maximum likelihood, log-likelihood, numerical optimization, neural networks, regularization, and Bayesian estimation.

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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Causal AI. The section links point to the parts of the book it draws on.