The correct answer is: B. The proportion of true positive predictions among all positive predictions.
Precision is a measure of a model’s ability to correctly identify positive cases. It is calculated by dividing the number of true positive predictions by the total number of positive predictions. A high precision indicates that the model is good at identifying positive cases, while a low precision indicates that the model is more likely to incorrectly identify negative cases as positive.
Option A is incorrect because it refers to the proportion of true positives, not the proportion of true positive predictions. Option C is incorrect because it refers to the proportion of false positives, not the proportion of true positive predictions. Option D is incorrect because it refers to the proportion of true positives, not the proportion of true positive predictions.