Basics

Question 1

Define sensitivity

Answer 1

The ability to identify positive results
The ability to detect small amounts of analyte
Proportion of people that have the disease that will test positive

Question 2

Calculate sensitivity

Answer 2

Sensitivity = (TP/TP + FN) X 100

Question 3

Define specificity

Answer 3

The ability to identify negative results
The selectivity of an assay reaction
Proportion of people known not to have a dz that will test negative for it

Question 4

Calculate specificity

Answer 4

Specificity = (TN/TN + FP) X 100

Question 5

Define Type I error (α)

Answer 5

false positive rate

Question 6

Calculate Type I error (α)

Answer 6

1 – specificity

Question 7

Define Type II error (β)

Answer 7

false negative rate

Question 8

Calculate Type II error (β)

Answer 8

1- sensitivity

Question 9

Define PPV

Answer 9

Proportion of positive test results that are true positives (correct diagnoses)

Question 10

Calculate PPV

Answer 10

Positive Predictive Value (Precision Rate) = TP/TP + FP (total positive calls)

Question 11

Define NPV

Answer 11

Proportion of negative test results that are true negatives (correct diagnoses)

Question 12

Calculate NPV

Answer 12

Negative Predictive Value = TN/TN + FN (total negative calls)

Question 13

As the prevalence of a condition increases, does the sample size required to detect the condition increase or decrease?

Answer 13

Decrease

Question 14

Does the number of animals that must be sample in order to achieve a certain level of confidence increase or decrease as the colony size decreases?

Answer 14

Increase (BB pg 383)