Statistics Flashcards
Attributable risk (AR)
Or
Risk difference (RD)
[a/(a+b)] - [c/(c+d)]
Draw box
X-axis disease: + or -
Y-axis exposure:
+
or
-
+ + = a; e+ d- = b; e- d+ = c; - - = d
Attributable risk %
ARx100%/[a/(a+b)]
Draw box
X-axis disease: + or -
Y-axis exposure:
+
or
-
+ + = a; e+ d- = b; e- d+ = c; - - = d
False negative
1- sensitivity
False positive
1 - specificity
Cumulative incidence
new cases in a given time period/
Total population at risk
Incidence rate
new cases of disease in a given time period/
Person-time years of observation
Likelihood ratios (LR)
LR+ (positive test) =
Sensitivity/(1-specificity)
LR- (negative test) =
(1- sensitivity)/specificity
Mortality rate, BW specific
deaths in specific BW categoryx1000/
# births in same BW category
Mortality rate, fetal
Fetal deaths x 1000/
(Live birth + fetal deaths)
Mortality rate, infant
Infant death (≤1 yo)x1000/
Live births
Mortality rate, neonatal
Neonatal deaths <28d x 1000/
Live births
*Can further divide to <7d and >7d but <28d
Mortality rate, perinatal
(Fetal deaths ≥ 28wk GA + neonatal deaths<7d)x1000/
(Live births+fetal deaths ≥28d GA)
Mortality rate, postnatal
Postneonatal deaths (28-364d)x1000/
Live births
NPV
d/(c+d) = TN/(FN+TN)
Draw box
X-axis disease: + or -
Y-axis test+:
+
or
-
+ + = a; e+ d- = b; e- d+ = c; - - = d
NNT
1/(A+B)
If A = events in the control/non exposed group = c/(c+d)
B = events in the treated/exposed group = a/(a+b)