MKSAP Biostatistics UPDATED ACTUAL Exam Questions and CORRECT Answers

MKSAP Biostatistics UPDATED ACTUAL
Exam Questions and CORRECT Answers
Sensitivity - CORRECT ANSWER - The ability of a test to detect a disease when it is truly
present.


Specificity - CORRECT ANSWER - The ability of a test to exclude disease when it is
truly absent.


ROC curve - CORRECT ANSWER - Graphed as sensitivity (y-axis) vs 1-specificity (x-
axis). When comparing to or more tests, the test w/ the greatest overall accuracy will have the
largest area under the ROC graph.


How does prevalence affect predictive values? Sensitivity? Specificity? - CORRECT
ANSWER - As prevalence increases, PPV increases and NPV decreases. It does not affect
sensitivity or specificity.


What is likelihood ratio and how it is calculated? - CORRECT ANSWER - LR is the odds
of having a disease independent of the prevalence.


LR+ = Sensitivity/ (1-specificity)
LR- = (1-sensitivity)/ Specificity


LR+ of 2, 5, or 10 increases the probability of disease by about 15%, 30%, and 45%.


Calculate absolute risk - CORRECT ANSWER - AR = patients w/ event in group/ total
patients in group


Calculate relative risk - CORRECT ANSWER - RRR = experimental event rate/ control
event rate