Accuracy, precision, recall

Formulated in words

accuracy = [$\frac{\text{something}}{\text{something}}$ ]

precision = [...]

recall = [...]

Pathalogical and benign examples

Are false positives dangerous? Are false negatives dangerous? Poor precision affords many false positives. Poor recall affords many false negatives. If the true/false meaning of any test is reversed, false positives become false negatives and vice versa.

• Poor precision is pathalogical: COVID19 testing where positive represents [having/being free of the virus?].
• Poor precision is benign: COVID19 testing, where a positive represents [having/being free of the virus?].
• Poor recall is pathalogical: COVID19 testing, where a positive represents [having/being free of the virus?].
• Poor recall is benign: COVID19 testing where positive represents [having/being free of the virus?].