Quality Progress - May 2017 - 25

The ability to form a good working hypothesis is an
essential part of any thorough root cause analysis (RCA), but is a subject that has garnered little
previous attention.
When performing RCA, it can be helpful to first
form a tentative hypothesis to give investigators
something concrete that can be evaluated and potentially move the investigation forward. Knowing the
five characteristics that make a good hypothesis will
provide investigators even stronger footing on which
to move their work forward.
A tentative hypothesis, also known as a working
hypothesis, provides a starting point for an investigation.1 Granted, the hypothesis may be wrong, but
having a working hypothesis gives you something
that can be evaluated. The hypothesis can be rejected
if it is found to be incorrect, of course, and ideally,

Just the
Facts
Forming a good
hypothesis is an
important part of
performing any
empirical root
cause analysis
because it gives
investigators a
starting point for
problem solving.
To form a more
robust hypothesis, you must
incorporate five
virtues, or characteristics, into
it: conservatism,
modesty, simplicity, generality and
refutability.

new information may have been gained while evaluating the hypothesis.
Suppose machined parts are found to be rusted.
An investigator may hypothesize that the parts are
wet with coolant when sent to the warehouse. This
hypothesis can be evaluated by determining whether
parts are indeed wet when sent to the warehouse.
If the failure is sporadic, a simple experiment can be
performed by intentionally wetting sample parts with
coolant and storing them in the warehouse. The parts
would be checked periodically to see whether they
have rusted.
A working hypothesis can be used to move an
issue forward when the problem's cause is unknown.
Remember, it's OK for a hypothesis to be wrong. It is
better to quickly discard many incorrect hypotheses
and reach the correct conclusion than to insist with

Jump-start your root cause analysis with a good hypothesis that
incorporates five essential virtues | by Matthew Barsalou

qualityprogress.com ❘ May 2017

QP 25


http://www.qualityprogress.com

Table of Contents for the Digital Edition of Quality Progress - May 2017

Seen and Heard
Expert Answers
Progress Report
Mr. Pareto Head
Field Notes
Mind the Gaps
Solid Footing
Are These the Same?
New Tricks for an Old Tool
Innovation Imperative
Experience More
Career Coach
Statistics Spotlight
Standard Issues
Marketplace
Footnotes
Back to Basics
Quality Progress - May 2017 - intro
Quality Progress - May 2017 - cover1
Quality Progress - May 2017 - cover2
Quality Progress - May 2017 - 1
Quality Progress - May 2017 - 2
Quality Progress - May 2017 - 3
Quality Progress - May 2017 - 4
Quality Progress - May 2017 - 5
Quality Progress - May 2017 - Seen and Heard
Quality Progress - May 2017 - Expert Answers
Quality Progress - May 2017 - Progress Report
Quality Progress - May 2017 - Mr. Pareto Head
Quality Progress - May 2017 - 10
Quality Progress - May 2017 - 11
Quality Progress - May 2017 - Field Notes
Quality Progress - May 2017 - 13
Quality Progress - May 2017 - 14
Quality Progress - May 2017 - 15
Quality Progress - May 2017 - Mind the Gaps
Quality Progress - May 2017 - 17
Quality Progress - May 2017 - 18
Quality Progress - May 2017 - 19
Quality Progress - May 2017 - 20
Quality Progress - May 2017 - 21
Quality Progress - May 2017 - 22
Quality Progress - May 2017 - 23
Quality Progress - May 2017 - Solid Footing
Quality Progress - May 2017 - 25
Quality Progress - May 2017 - 26
Quality Progress - May 2017 - 27
Quality Progress - May 2017 - 28
Quality Progress - May 2017 - 29
Quality Progress - May 2017 - Are These the Same?
Quality Progress - May 2017 - 31
Quality Progress - May 2017 - 32
Quality Progress - May 2017 - 33
Quality Progress - May 2017 - 34
Quality Progress - May 2017 - 35
Quality Progress - May 2017 - New Tricks for an Old Tool
Quality Progress - May 2017 - 37
Quality Progress - May 2017 - 38
Quality Progress - May 2017 - 39
Quality Progress - May 2017 - 40
Quality Progress - May 2017 - 41
Quality Progress - May 2017 - 42
Quality Progress - May 2017 - 43
Quality Progress - May 2017 - Innovation Imperative
Quality Progress - May 2017 - 45
Quality Progress - May 2017 - 46
Quality Progress - May 2017 - Career Coach
Quality Progress - May 2017 - 48
Quality Progress - May 2017 - 49
Quality Progress - May 2017 - Statistics Spotlight
Quality Progress - May 2017 - 51
Quality Progress - May 2017 - 52
Quality Progress - May 2017 - 53
Quality Progress - May 2017 - Standard Issues
Quality Progress - May 2017 - 55
Quality Progress - May 2017 - 56
Quality Progress - May 2017 - 57
Quality Progress - May 2017 - Marketplace
Quality Progress - May 2017 - 59
Quality Progress - May 2017 - Footnotes
Quality Progress - May 2017 - 61
Quality Progress - May 2017 - 62
Quality Progress - May 2017 - 63
Quality Progress - May 2017 - Back to Basics
Quality Progress - May 2017 - cover3
Quality Progress - May 2017 - cover4
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