
242 Part II The Step-by-Step Guide to the TIQM Quality System
UCL
Zone A
Zone B
Zone C
Zone C
Zone B
Zone A
LCL
1
1
Source: Lloyd S. Nelson, Director of Statistical Methods, Nashua Corporation,
New Hampshire, as cited in Goal/QPC: The Memory Jogger II, 1994, p. 46, or The Six Sigma Memory Joggen II, p. 85.
2a
2a
2b
2b
2c
2c
2d
2d
2e
2e
2f
2f
x
=
Figure 5-33: Out-of-Control Condition Indicators
The process is considered Out-of-Control if any of the following conditions
is true:
8
1. One or more points fall outside of the control limits
2. When the Control Chart is divided into zones, as shown in Figure 5-33:
2a. Two points, out of three consecutive points, are on the same side of
the average in Zone A or beyond
2b. Four points, out of five consecutive points, are on the same side of the
average in Zone B or beyond
2c. Nine consecutive points are on one side of the average
2d. There are six consecutive points, increasing or decreasing
2e. There are fourteen consecutive points that alternate up and down
2f. There are fifteen consecutive points within Zone C (above and below
the average)
P2.8.5.2
If the process is Out-of-Control, establish a Process Improvement ini-
tiative to identify the Root Cause or Causes and eliminate them first.
See “TIQM P4 Improve Information Process Quality” in Chapter 7.
tip If a process is Out-of-Control, it must be stabilized and brought In
Control before you can Im ...