Exam 2: Understanding Predictive Values

Question 1

What is positive predictive value?

Answer 1

Among the positive tests, the proportion of those that are truly positive

Question 2

What is negative predicitve value?

Answer 2

Among the negative tests, the proportion of those that are truly negative

Question 3

How does higher sensitivity impact predictive value?

Answer 3

It improves NPV and helps identify the disease negative

It rules OUT disease

Question 4

How does lower specificity change predictive value?

Answer 4

Decreases PPV

Lower specificity means more false positives

Question 5

What does a more sensitive test do?

Answer 5

Reduces false negatives and increases NPV

SNout: helps to rule out disease as it identifies the disease negative

Question 6

What does a more specific test do?

Answer 6

Reduces false positives and improves PPV

SPin: rules in disease as it will identify the disease positive

Question 7

If you had a dog that you do not think has HW disease, which test is most likely to properly classify this dog?

Answer 7

Specific test

Question 8

If you had a dog you suspected of having HW disease, which test would properly classify this do?

Answer 8

Sensitive test