Confusion matrices, precision, recall, F1, ROC AUC, RMSE, calibration, imbalanced data and hyperparameter tuning.
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- What is a confusion matrix?
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A table showing true positives, true negatives, false positives, and false negatives for a classifier's predictions
- What does a true positive (TP) represent?
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A correct prediction where the model predicted positive and the actual label is positive
- What does a false positive (FP) represent?
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An incorrect prediction where the model predicted positive but the actual label is negative, also called Type I error
- What does a true negative (TN) represent?
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A correct prediction where the model predicted negative and the actual label is negative
- What does a false negative (FN) represent?
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An incorrect prediction where the model predicted negative but the actual label is positive, also called Type II error
- What is precision?
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The proportion of positive predictions that were correct, calculated as TP / (TP + FP)
- What is recall?
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The proportion of actual positives that were correctly identified, calculated as TP / (TP + FN)
- What is specificity?
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The proportion of actual negatives that were correctly identified, calculated as TN / (TN + FP)
- What is the F1 score?
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The harmonic mean of precision and recall, calculated as 2 * (precision * recall) / (precision + recall)
- What trade-off exists between precision and recall?
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Increasing one typically decreases the other; the choice depends on the cost of false positives versus false negatives for your problem
- What is a ROC curve?
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A plot of True Positive Rate (y-axis) versus False Positive Rate (x-axis) at various classification thresholds
- What does AUC measure?
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The area under the ROC curve; it represents the probability that the model ranks a random positive example higher than a random negative example
- What is the True Positive Rate (TPR)?
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The fraction of actual positives correctly identified, equivalent to recall, calculated as TP / (TP + FN)
- What is the False Positive Rate (FPR)?
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The fraction of actual negatives incorrectly classified as positive, calculated as FP / (FP + TN)
- What does an AUC of 0.5 indicate?
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The model performs no better than random chance, essentially flipping a coin