VIBS 413-Exam 1 UPDATED QUESTIONS
AND CORRECT ANSWERS
Validity - CORRECT ANSWER ability of a test to distinguish between those who have
disease and those who do not
Sensitivity - CORRECT ANSWER ability of a test to correctly identify those who have
disease
TP/TP+FN
Specificity - CORRECT ANSWER ability of a test to correctly identify those who do
not have disease
TN/TN+FP
Dichotomous test - CORRECT ANSWER results will be positive or negative
Relatively high test cutoff - CORRECT ANSWER end result is low sensitivity but high
specificity; no false positives but lots of false negatives
Relatively low test cutoff - CORRECT ANSWER end result is high sensitivity but low
specificity; no false negatives but lots of false positives
Screening program - CORRECT ANSWER large group screens positive then they are
subject to more testing
Downside: anxiety in patients, debilitating to patients, burden to healthcare system
Sequential testing (two stage) - CORRECT ANSWER less expensive/invasive test first,
those who screen positive are followed up with a more invasive test
Major gain in specificity but loss in sensitivity
, Simultaneous testing - CORRECT ANSWER 2 tests run simultaneously and positive
results determined from either or both test results
Major gain in sensitivity but loss in specificity
PPV (positive predictive value) - CORRECT ANSWER if the test results are positive
what is the probability that the patient has the disease
TP/total positives
NPV (negative predictive value) - CORRECT ANSWER if the test results are negative
what is the probability that the patients is disease free
TN/total negatives
Predictive value - CORRECT ANSWER affected by two factors:
Prevalence of disease in population (lower prevalence means lower PV)
Specificity of test
Reliability (repeatability) - CORRECT ANSWER depends on
Intrasubject variation (time of day)
Intraobserver variation (interpreting radiograph)
Interobserver variation (agree or disagree with other people interpreting test results)
Kappa Statistic - CORRECT ANSWER element of chance that observers may agree or
disagree on test results
Epidemiology - CORRECT ANSWER study of the distribution and determinants of
health-related states or events in specified populations and the application of this study to
control health problems
Epidemiologic triad - CORRECT ANSWER external agent, susceptible host, favorable
environment
AND CORRECT ANSWERS
Validity - CORRECT ANSWER ability of a test to distinguish between those who have
disease and those who do not
Sensitivity - CORRECT ANSWER ability of a test to correctly identify those who have
disease
TP/TP+FN
Specificity - CORRECT ANSWER ability of a test to correctly identify those who do
not have disease
TN/TN+FP
Dichotomous test - CORRECT ANSWER results will be positive or negative
Relatively high test cutoff - CORRECT ANSWER end result is low sensitivity but high
specificity; no false positives but lots of false negatives
Relatively low test cutoff - CORRECT ANSWER end result is high sensitivity but low
specificity; no false negatives but lots of false positives
Screening program - CORRECT ANSWER large group screens positive then they are
subject to more testing
Downside: anxiety in patients, debilitating to patients, burden to healthcare system
Sequential testing (two stage) - CORRECT ANSWER less expensive/invasive test first,
those who screen positive are followed up with a more invasive test
Major gain in specificity but loss in sensitivity
, Simultaneous testing - CORRECT ANSWER 2 tests run simultaneously and positive
results determined from either or both test results
Major gain in sensitivity but loss in specificity
PPV (positive predictive value) - CORRECT ANSWER if the test results are positive
what is the probability that the patient has the disease
TP/total positives
NPV (negative predictive value) - CORRECT ANSWER if the test results are negative
what is the probability that the patients is disease free
TN/total negatives
Predictive value - CORRECT ANSWER affected by two factors:
Prevalence of disease in population (lower prevalence means lower PV)
Specificity of test
Reliability (repeatability) - CORRECT ANSWER depends on
Intrasubject variation (time of day)
Intraobserver variation (interpreting radiograph)
Interobserver variation (agree or disagree with other people interpreting test results)
Kappa Statistic - CORRECT ANSWER element of chance that observers may agree or
disagree on test results
Epidemiology - CORRECT ANSWER study of the distribution and determinants of
health-related states or events in specified populations and the application of this study to
control health problems
Epidemiologic triad - CORRECT ANSWER external agent, susceptible host, favorable
environment
