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Area under the curve

As explained in Statistics Slam Dunk

AUC is the area under a receiver operating characteristic curve, measuring a binary classifier's ability to rank positive cases above negative cases.

Area under the curve (AUC) summarizes how well a binary classification model distinguishes positive cases from negative cases. It is calculated from the receiver operating characteristic (ROC) curve, which plots specificity against sensitivity. An AUC of 1 represents perfect discrimination, 0.5 represents random chance, and higher values indicate stronger overall discriminatory power. section 14.6.2

Unlike error rate and accuracy, which count individual classifications at a chosen threshold, AUC evaluates the model's overall ability to separate the two classes. Sensitivity and specificity therefore provide complementary information rather than interchangeable results. section 14.6.2

NBA playoff prediction

A logistic regression predicted whether NBA teams qualified for the playoffs. Passing actual outcomes and predictions to pROC's roc() function produced an AUC of 0.73, indicating fairly strong predictive performance. The ROC curve can then be drawn with base R's plot() function. Comparing a second model shows why AUC matters: one model can have higher sensitivity while another has higher specificity, yet their AUCs can be essentially equal. section 14.6.2

Use AUC to:

  • Compare binary classification models by overall discriminatory power. section 14.6.2
  • Interpret ROC plots alongside sensitivity, specificity, accuracy, and error rate. section 14.6.2

How Statistics Slam Dunk covers it

How deep it goes
Defines AUC, gives benchmark values, contrasts it with classification error, and demonstrates calculation without developing its mathematical internals.
Examples
Uses NBA playoff qualification predictions, a logistic regression, an AUC of 0.73, and ROC plots to compare models.
What it assumes
Assumes binary outcomes, logistic regression, sensitivity, specificity, and confusion-matrix interpretation.
What you can do after
Evaluate binary classification models with pROC's roc() function and visualize their ROC curves using base R.
How it connects
Connects AUC with ROC curves, sensitivity, specificity, accuracy, error rate, confusion matrices, and logistic regression.

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Related concepts

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