Table 3. Formulas and values involved in plotting the LC-CUSUM curve with an acceptable ECV failure rate of 30%.

Variable	Value
p0—unacceptable ECV failure rate	0.7
p1—acceptable ECV failure rate	0.3
α—probability of the type I error	0.05
β—probability of the type II error	0.20
P=ln (p1/p0)	−0.847
Q=ln [(1−p0)/(1−p1)]	−0.847
s=Q/(P+Q)	0.5
1−s	0.5
a=ln [(1−β)/α]	2.77
b=ln [(1−α)/β]	1.56
H=a/(P+Q)	−1.635

ECV, external cephalic version.