Evals

Question 1

accuracy

Answer 1

ratio of correct predictions / total predictions

Question 2

precision

Answer 2

ratio of true positives to sum of true positives and false positives

Question 3

recall

Answer 3

ratio of true positives to sum of true positives and false negatives (and remember a false negative is the other type of positive, so this metric is essential ratio of true positives / actual positives

Question 4

other names for recall

Answer 4

sensitivity, or true positive rate

Question 5

F1 score

Answer 5

the harmonic mean of precision and recall

Question 6

how to calculate harmonic mean

Answer 6

reciprocal of the arithmetic mean of the reciprocals

Question 7

when is harmonic mean useful?

Answer 7

it is the appropriate measure of central tendency when dealing with rates

In the context an example with speeds (e.g. traveling 1 min at 20mph, 1 min at 30mph, 1 min at 60mph, the harmonic mean gives the average speed over the entire trip, assuming constant time intervals)