Page 197 - The Handbook for Quality Management a Complete Guide to Operational Excellence

184 P r o c e s s C o n t r o l Q u a n t i f y i n g P r o c e s s Va r i a t i o n 185

Shipment Units Flaws-per-
Number (Crates) Flaws Unit
1 1 47 47
2 1 42 42
3 1 55 55
4 1 51 51
5 1 46 46
6 1 61 61
7 1 39 39
8 1 44 44
9 1 41 41
10 1 51 51
11 2 88 44
12 2 101 50.5
13 2 101 50.5
14 1 40 40
15 1 48 48
16 1 47 47
17 1 50 50
18 1 48 48
19 1 57 57
20 1 45 45
21 1 43 43
22 2 105 52.5
23 2 98 49
24 2 100 50
25 2 96 48
TOTALS 32 1544

Table 9.9 Raw Data for u Chart

that is, we will be counting crates rather than the peaches themselves.
Normally, samples consist of one crate per shipment. However, when
part-time help is available, samples of two crates are taken.
Using the above data the centerline and control limits are found as
follows:

subgroup count of occurrences
u =
e
subgroup size in units

09_Pyzdek_Ch09_p151-208.indd 184 11/21/12 1:42 AM