Quality Progress - January 2016 - 50
BACK TO BASICS
BY DAVID M. RUCKER
Get to the Root of It
Use an is/is not comparative analysis tool to pinpoint the problem
WE'VE ALL been there before-an
a problem occurs and-just as impor-
elusive field failure sparks customer com-
tantly-does not occur.
During a recent workshop with shop floor
plaints and warranty claims, threatening
The process tends to work best with
supervision and quality personnel, a team
to curtail future orders. Ambiguous, con-
an active facilitator who challenges state-
attacked a major field failure of a critical
flicting field reports of failure modes and
ments made, such as "Do we have data to
cast component. In two days, the team
products affected pour in. Root cause
back that up?" and "Do we really know
identified the failure mode, structured
theories sprout like wildfire, coupled
that to be true?"
the data collection and used comparative
The facilitator should constantly re-
with emphatic statements like, "We've
analysis to find the root cause.
mind the team of the difference between
The supplier of one casting had
At times like these, quality profession-
facts and opinions. Team member knowl-
repaired bad castings by drilling out
als need to inject reason, logic and quick
edge and experience is useful; it's impor-
slag-the bottoming of the drill removed
but disciplined approaches to clarify the
tant, however, to clarify the difference.
wall thickness that led to the failure. The
never had this problem before!"
When data are not available to back up
situation, identify the root cause and
a position, ask yourself whether it could
resolve the issue.
be quickly collected. To separate theories
An is/is not comparative analysis is a
defective parts were quickly quarantined,
avoiding a potential $600,000 recall.
This process takes the emotion out
powerful tool for quickly honing in on
from opinions, could you conduct an im-
of analysis at a stressful time. It also
the root cause. Use this deductive logic
mediate experiment as proof? Add the re-
allows the group to slow down and move
tool in the measure phase of the define,
sults of ensuing fieldwork to the diagram.
deliberately at a time when many want to
The matrix helps organize all relevant
measure, analyze, improve and control
process to determine what is in scope
knowledge and information about the
and what is not going to be considered at
problem in one handy reference.
For many low hanging fruit-type quality issues, this tool leads directly to the
Classifying the problem in the cat-
this stage (see Figure 1).
jump to conclusions.
root cause. For more complex problems,
egories of time-to-time, part-to-part or
it helps identify the key performance
functional group of four to eight people
within-part defect assists the team in
variables requiring further study. QP
who represent all facets of the issue. Post
understanding how to structure the data-
the diagram in Figure 1 on a flipchart,
gathering process. Common sense and a
whiteboard or projector screen to engage
simple deductive reasoning process leads
the whole team.
the team to a conclusion and problem
The process works best with a cross-
Once the root cause is found, confirm
The method involves deliberating and
the hypothesis and turn the defect off
answering a series of questions designed
and on in the capping run of the simpli-
to pinpoint when, where and how often
fied design of experiments.
Is/is not comparative analysis
object has the
What is the specific
50 QP * www.qualityprogress.com
DAVID M. RUCKER is president of
Rucker & Associates, a consulting firm
in Raleigh, NC. He holds a master's
degree in mechanical engineering
from Southern Methodist University
in Dallas. Rucker is a senior member
of ASQ and a frequent contributor to
ASQ's Lean Division newsletter.
/ FIGURE 1
have the defect
but does not?
What other defects
could be observed
but are not?
Table of Contents for the Digital Edition of Quality Progress - January 2016
According to Plan
Use Your Head
Stakeholder Management 101
All About Data
Eight Simple Steps
Which Six Sigma Metric Should I Use?
Turning ‘Who’ Into ‘How’
In the Beginning
Outputs and Outcomes
That’s So Random—Or Is It?
Improving a System
Putting It All on the Table
Know the Drill
It’s Fun To Work With an F-M-E-A
Solve Problems With Open Communication
Tell Me About It
Separate the Vital Few From the Trivial Many
To DMAIC or Not to DMAIC?
Breaking It Down
1 + 1 = Zero Defects
Curve Your Enthusiasm
Make a Choice
What Is a Fault Tree Analysis?
Successful Relationship Diagrams
The Benefits of PDCA
Return on Investment
The Art of Root Cause Analysis
Why Ask Why?
Get to the Root of It
Checks and Balances
Clearing SPC Hurdles
Supplier Selection and Maintenance
Building a Quality Team
Plan Experiments to Prevent Problems
Quality Progress - January 2016