Equations Flashcards
1
Q
prevalence
A
(incidence)(duration)
or
(tp+fn)/ (tp+fp+tn+tp)
2
Q
sensitivity
A
tp/ (tp+fn)
3
Q
specificity
A
tn/ (tn+fp)
4
Q
PPV
A
tp/ (tp+fp)
5
Q
NPV
A
TN/ (TN+ FN)
6
Q
accuracy
A
(tp+tn)/ (tp+tn+fp+fn)
7
Q
positive liklihood ratio
A
sensitivity/ (1-specificity)
8
Q
negative liklihood ratio
A
(1-sensitivity)/ specificity
9
Q
incidence
A
cases/ total time
10
Q
needed to treat
A
1/ absolute risk reduction
11
Q
needed to harm
A
1/ attributable risk
12
Q
odds ratio
A
ad/bc (“cross products”)
13
Q
Relative Risk
A
(a/a+b)/(c/c+d)
14
Q
z score
A
(observed value- population mean)/ population standard deviation
15
Q
standard error
A
sample standard deviation/ square root of sample size
16
Q
chi squared
A
(observed - expected) ^2/ expected
