Chapter 13.6, Problem 13.45ACB

Monitoring surgery complications. An article on the use of control charts for monitoring the proportion of post operative complications at a large hospital was published in the International Journal for Quality in Health Care (October 2010). A random sample of surgical procedures was selected each month for 30 consecutive months, and the number of procedures with postoperative complications was recorded. The data are listed in the accompanying table.

a. Identify the attribute of interest to the hospital.

b. What are the rational subgroups for this study?

Month	Complications	Procedures Sampled
1	14	105
2	12	97
3	10	115
4	12	100
5	9	95
6	7	111
7	9	68
8	11	47
9	9	83
10	12	108
11	10	115
12	7	94
13	12	107
14	9	99
15	15	105
16	13	no
17	7	97
18	10	105
19	8	71
20	5	48
21	12	95
22	9	110
23	7	103
24	9	95
25	15	105
26	12	100
27	8	116
28	2	110
29	9	105
30	10	120
Totals	294	2,939

c. Find the value of $\bar{p}$ for use in a p-chart.

d. Compute the proportion of post-op complications in each month.

e. Compute the critical boundaries for the p-chart (i.e.. UCL, LCL, Upper A-B boundary, etc.).

f. Construct a p-chart for the data.

g. Interpret the chart. Does the process appear to be in control? Explain.