 # Difference between AIC and BIC When it comes to choosing an appropriate model for inference, statisticians have two main options: the maximum likelihood estimator (MLE) and the Bayesian inference (BI). In this post, we will discuss the difference between AIC and BIC, two popular measures of model fit. We will also see how these measures can be used to compare different models.

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## What is AIC?

• AIC, also known as the Akaike Information Criterion, is a statistical method used to assess the goodness of fit of a model. In other words, it allows us to compare different models and choose the one that best explains the data. AIC is based on the concept of relative entropy, which measures the difference between two probability distributions. In the context of AIC, we are comparing the fitted model to the null model, which is the simplest possible model.
• The AIC value for a given model is calculated as follows: AIC = -2 log L + 2k, where L is the likelihood of the data given the model and k is the number of parameters in the model. The AIC can be used to compare non-nested models, which means that it can be used even if the models are not directly comparable. For example, we could use AIC to compare a linear regression model to a logistic regression model.
• AIC can also be used to compare nested models, which are models that are nested within each other. For example, we could use AIC to compare a linear regression model with one predictor variable to a linear regression model with two predictor variables.

## What is BIC?

BIC, or the Bayesian Information Criterion, is a statistical tool that is used to compare the goodness of fit of two models. BIC is based on the idea that the best model is the one that maximizes the likelihood of the data, while also penalizing the number of parameters in the model. This ensures that the model is not overfitted to the data. BIC can be used in a variety of settings, including regression analysis and machine learning. In general, BIC is a valuable tool for statisticians and data scientists who need to compare different models.

## Difference between AIC and BIC

AIC and BIC are both methods of estimating the best model from a set of models. AIC is Akaike’s Information Criterion, while BIC is the Bayesian Information Criterion. Both AIC and BIC estimate the goodness of fit of a model to data, but AIC does so by maximizing the likelihood function while BIC does so by minimizing the Bayesian information loss function.

AIC is generally considered to be more reliable than BIC, but BIC is faster to compute. AIC is also affected by overfitting, while BIC is not. Ultimately, both AIC and BIC can be useful tools for model selection, but AIC is typically more accurate.

## Conclusion

The difference between AIC and BIC is an important distinction to make when considering which model to use for your data analysis. In general, AIC is a better choice if you are looking for the most accurate estimate of error while BIC is more appropriate if you want to find the best-fitting model. However, as with all things in statistics, there is no single answer that fits every situation; it’s important to consider your specific data and goals before making a decision.