Table 1

Cumulative sum charting design for monitoring cataract surgery performance

Specifications	Parameter	Parameter
Outcome measure for purpose of performance monitoring as determined by the user	Posterior capsular rupture	Postoperative refracted visual acuity
Acceptable rate of performance for the outcome measure specified as determined by the user, π1	5%	10%
Unacceptable rate of performance for the outcome measure specified as determined by the user, π2	10%	20%
Reference value k, calculated based on π1 and π2 using methods described by Hawkins and Olwell.17	0.072	0.145
*h, †IC-ARL and ‡OC-ARL, calculated based on k using methods described by Hawkins and Olwell.17	*h=0.50	*h=1.45
	†IC-ARL=20	†IC-ARL=52
	‡OC-ARL=10	†OC-ARL=16

h and the ARLs determine the degree of sensitivity of the chart and are selected by the user.
↵* h, decision interval.
↵† IC-ARL, in control-average run length.
↵‡ OC-ARL, out of control-average run length.