Model Evaluation and Improvement

Question 1

Define F1 score

Answer 1

The Harmonic mean of precision and sensitivity:

F1=(2TP)/(2TP+FP+FN)

Where:
TP=# True Positives
FP=# False Positives
FN=# False Negatives

Question 2

Define True Positive Rate

Answer 2

TPR=TP/P=TP/(TP+FN)

Where:
TP=# True Positives
FN=# False Negatives
P=Total Actual Positives

Note: TPR (True Positive Rate)=Sensitivity=Recall=Hit Rate

Question 3

Define True Negative Rate

Answer 3

TNR=TN/N=TN/(TN+FP)

Where:
TN=# True Negatives
FP=# False Positives
N=Total Actual Negatives

Note: TNR (True Negative Rate)=Specificity=Selectivity

Question 4

Define Positive Predictive Value

Answer 4

PPV=TP/(TP+FP)

Where:
TP=# True Positives
FP=# False Positives

Positive Predictive Value = Precision

Question 5

Define Negative Predictive Value

Answer 5

NPV=TN/(TN+FN)

Where:
TN=# True Negatives
FN=# False Negatives