PUBH 6003 QUIZ 4 CERTIFICATION
EVALUATION QUESTIONS ANSWERS
COMPLETE SOLUTION VERIFIED PASS
●● Characteristics of disease that make it a good candidate for screening
Answer: -disease is serious (associated with mortality or severe health
consequences)
-treatment is more effective if implemented before symptoms develop
-disease has detectable preclinical phase (DPCP - fairly long/prevalent in
target population)
●● sensitivity
Answer: of those who have the disease, how many test positive
Limits false negatives
●● specificity
Answer: of those without disease, how many test negatively
Limits false positives
●● sequential screening
, Answer: increases net specificity, decreases net sensitivity (positive
series more likely to be TP)
1st test if negative - stop, if positive - second test
second test if positive - diagnostic test
net sensitivity = + on BOTH tests / total with disease
net specificity = - on EITHER test / total without disease
●● parallel screening
Answer: increases net sensitivity, decreases net specificity (false
positives more likely)
net sensitivity = + on EITHER test / total with disease
net specificity = - on BOTH tests / total without disease
●● Positive predictive value
Answer: if test positive, the probability you actually have the disease
●● Negative predictive value
Answer: if test negative, probability you don't have the disease
EVALUATION QUESTIONS ANSWERS
COMPLETE SOLUTION VERIFIED PASS
●● Characteristics of disease that make it a good candidate for screening
Answer: -disease is serious (associated with mortality or severe health
consequences)
-treatment is more effective if implemented before symptoms develop
-disease has detectable preclinical phase (DPCP - fairly long/prevalent in
target population)
●● sensitivity
Answer: of those who have the disease, how many test positive
Limits false negatives
●● specificity
Answer: of those without disease, how many test negatively
Limits false positives
●● sequential screening
, Answer: increases net specificity, decreases net sensitivity (positive
series more likely to be TP)
1st test if negative - stop, if positive - second test
second test if positive - diagnostic test
net sensitivity = + on BOTH tests / total with disease
net specificity = - on EITHER test / total without disease
●● parallel screening
Answer: increases net sensitivity, decreases net specificity (false
positives more likely)
net sensitivity = + on EITHER test / total with disease
net specificity = - on BOTH tests / total without disease
●● Positive predictive value
Answer: if test positive, the probability you actually have the disease
●● Negative predictive value
Answer: if test negative, probability you don't have the disease
