2x2 table
(EER-CER)/CER (intervention)
relative benefit increase (RBI)
(CER - EER)/CER (intervention)
relative risk reduction (RRR)
(a/a+b)/(c/c+d) (prognostic)
risk ratio
OR <1 for an adverse outcome (prognostic)
Odds against adverse outcome; prognostic factor is protective
c+d (diagnostic)
all participants who test negative
a+b (diagnostic)
all participants who test positive
a+c (diagnostic)
all participants with the condition
b+d (diagnostic)
all participants without the condition
c/(c+d) (intervention)
control event rate
a/(a+b) (intervention)
experimental event rate
1-sensitivity
false negative rate
c (diagnostic)
false negatives
1-specifity
false positive rate
b (diagnostic)
false positives
CER measures (intervention)
frequency of event (outcome of interest) in control group
EER measures (intervention)
frequency of event (outcome of interest) in the experimental group
LR- measures
likelihood that a negative result is observed in a person without the condition
LR+ measures
likelihood that a positive result is observed in a person with the condition
(1-sensitivity)/specificity
negative likelihood ratio
1/ABI (intervention)
number needed to treat (NNT)
1/ARR (intervention)
number needed to treat (NNT)
OR <1 for a positive outcome (prognostic)
odds against positive outcome; prognostic factor is harmful
OR >1 for an adverse outcome (prognostic)
odds favor the adverse outcome
OR >1 for a positive outcome (prognostic)
odds favor the positive outcome
(a/b)/(c/d); (ad)/(bc) (prognostic)
odds ratio
sensitivity/(1-specificity)
positive likelihood ratio
a/a+b (diagnostic)
positive predictive value
d/b+d (diagnostic)
specifity
odds ratio measures (prognostic)
the odds that somebody with the prognostic factor will develop the condition of interest
SnNout
with high sensitivity, a negative test rules out the diagnosis
SpPin
with high specificity, a positive test rules in the diagnosis
d/c+d (diagnostic)
Negative predictive value
NPV measures
ability to determine the actual proportion of people who don't have the condition based on a negative test
PPV measures
ability to determine the actual proportion of people with the condition based on a positive test
EER-CER (intervention)
absolute benefit increase (ABI)
CER-EER (intervention)
absolute risk reduction (ARR)
sensitivity measures
the test's ability to find true positives
d (diagnostic)
true negatives
a (diagnostic)
true positives
a/a+c (diagnostic)
sensitivity
specifity measures
the test's ability to find true negatives
