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DATA MANAGEMENT PLANS CAN REDUCE PROJECT CYCLE
TIMES
by Dave Wetzel, Ph. D.
Long project cycle times, frequently cited as an
impediment to Six Sigma success, can be accelerated
through the use of data management plans. When
employed as the first step in the Measure phase of
the DMAIC process, the plan provides Six Sigma
project teams with a highly structured planning
tool. It not only helps teams ask all the right
questions in the Measure phase, but also gives
insight into potential analysis and project
validation activities that will follow in later
phases. A data management plan (DMP) is the pivotal
document for project success, second only to a good
scope charter. DMP – Pivotal Measure Document The
data management plan should be developed either
during a training week or in a project team meeting.
It typically takes a team about two to four hours to
complete. The DMP can reduce project cycle times
significantly because a plan of attack – which
navigates a phase in which many project teams get
lost – has been quickly generated and agreed upon.
The plan helps the team to characterize, balance,
validate, graphically display and stratify its main
project metric. As shown in Table 1, the DMP has
four major sections: data description, data
collection and validation, graphical display and
project validation,
and analysis.
|
Table
1 |
|
1. Data Description |
|
Metric (Unit of Measure) |
Operational Definition
(Verbal or Formula) |
Family of Measure |
Data Type |
| Setup time
(minutes) |
Time elapsed
between last good part to acceptance of new
part |
T |
Continuous |
| Raw
materials dimensions (indices) |
Process
capability Cp/Cpk
per print |
Q |
Continuous |
| Scrap
(units) |
Non-conforming parts |
P |
Ordinal |
|
2. Data Collection
and Validation |
| Data
Source or Location |
Collector |
Sampling Plan |
MSA
Plan |
| Log |
Operator |
1/Set-up |
Paired
t-test and time study |
| Tag |
Receiving inspector |
1/Lot |
Gage R&R |
| Routing |
Operator |
1/Batch |
Paired t-test |
|
3. Graphical Display
and Project Validation |
|
Of Central Tendency and
Variation |
Of Time Ordered Data |
Main Desirability |
Comparative Experiment |
| Histogram |
IMR |
Decrease
mean |
Median test
and f-test |
| Histogram |
Xbar
and sigma |
More capable |
Gage R&R and
2 sample t-test |
| Bar chart |
p chart |
Decrease
mean |
Paired
t-test and attribute MSA |
|
4. Analysis |
|
Stratification Factors
(ANOVAs, et al) |
| By machine
and operator |
| By critical
dimension |
| By month,
center and machine |
Even before one can discuss collecting and
validating data, understanding the data description
– or the data inputs and outputs – is critical for a
successful data management plan.
Data Description
Fully defining process parameters (input) or product
characteristics (output) is the beginning of
data-based decision-making. Every metric has three
components which are required to fully describe it.
Identification of these three components should be:
conducted with the entire core and extended team so
any confusion is eliminated; reviewed by the project
sponsor, financial analyst and mentor; and reviewed
with any other relevant stakeholders. Completely
describing the main project metric communicates to
all stakeholders exactly what metric the project is
trying to improve and what balancing or
countermeasures are being employed.
The three components required to fully describe and
communicate main project metrics are the:
-
Metric itself: The attribute, variable or
rate that is changing. This is one word (i.e.,
time, rate, temperature, weight, concentration,
speed, pounds, index).
-
Descriptor: The information needed to
specifically identify the metric so it is not
confused with others. The descriptor should be
kept simple. Imagine describing the main project
metric to your parents, a child or a complete
stranger.
-
Unit of measure: This is the count or
scale (percent, count, units, dollars,
centimeters, rpm). The unit of measure should be
surrounded by brackets. It clearly identifies
the correct "family of measure" further on.
This section of the DMP requires the team to ask
three key questions designed to fully describe the
metrics: operational definitions, family of measure
and data type. There are many ramifications and
benefits for answering these questions thoughtfully
and accurately. These answers give clues to further
activities as far down the project road as the
Control phase.
Operational Definitions
The first question, operational definitions, can be
handled in one of two ways:
-
As a description in words, using a clear,
precise description of the factor being
measured.
-
As a mathematical formula, an operational
calculation or "an expression" in symbolic
logic.
One way to facilitate this effort and to prove that
clear operational definitions are important is to
have everyone anonymously write their interpretation
of the main project metric. How is the metric
calculated and explained? Responses to this question
often surprise team members who instantly note the
inconsistency, creativity and misunderstandings that
exist amongst even those closest to the project
metric and its effects. A benefit of clear
operational definitions will be further explored in
measurement system analysis, where poor operational
definitions can, at best, confuse and, at worse,
completely kill, a project.
Family of Measure
The second question to be considered at this point
in the DMP is family of measure (FoM). FoM is a much
underutilized concept. There are four basic families
of measure – productivity, financial, quality and
timeliness. Simpler versions are often used (i.e.,
quality, cost, speed) but the fuller version,
containing all four metrics, is the most beneficial.
FoM includes the four metrics, plus the use of
hybrids, which are combinations of any of the two.
The hybrids are rates, readily identifiable from
percentages, unit-less measures, or
numerators/denominators. Each FoM answers a
different question and has a different unit of
measure. It can be argued that differentiating
between productivity and quality is what Six Sigma
was originally all about. It is the story behind the
story when someone explains the Taguchi loss
function. It is what Motorola was after when it
started using process capability indices to describe
"how well" its processes, products and services
were. Process capability and customer satisfaction
indices are very different from productivity
metrics, and represent true quality metrics. Table 2
helps clarify the differences between the FoMs.
|
Table
2 |
|
Family of Measure |
Question |
Unit of Measure |
Examples |
|
P |
Productivity |
How many? |
Units |
Counts, units produced,
scrap, rework, repair |
|
F |
Financial |
How much? |
Dollars |
Cost, budgets, benefits,
profits |
|
Q |
Quality |
How well? |
Index |
Customer satisfaction,
process capability indices |
|
T |
Timeliness |
How fast? |
Time |
Cycle time, duration,
dwell time, shipping time |
|
?/? |
Any
Combination |
At what
rate? |
Percent |
Labor rates, yield,
return rates |
An
important use for FoM is to balance project measures
– ensure that a team does not focus on just one
measure at the expense of others. For example, speed
up the assembly line at the expense of lower yields
or shorten call time goals at the expense of the
customer experience. FoM also can be used to
identify project types. For example, a project type
within productivity can focus on increasing yield or
reducing scrap, while a project type within quality
can focus on improving customer satisfaction or
reducing variation.
Some organizations use a FoM matrix to help decide
project selection. For example, if the Six Sigma
effort is internally driven by productivity and
inventory initiatives, few customer and quality
projects are going to be selected.
Data Type
The third question teams should ask at this point in
the DMP development focuses on data type. One of the
biggest problems with data type is the many
different ways to describe it, ranging from the
scientific, statistical way to the layperson's way.
Helping team members distinguish between variable
data (where they measure the variable) and attribute
data (where they simply count it) can be useful.
-
Continuous or variable data – Any variable
measured on a continuum or scale that can be
infinitely divided
-
Examples: time, weight, temperature, speed
-
Always preferred over discrete/attribute
data
-
Discrete or attribute data – A count, proportion
or percentage of a characteristic or category
-
Nominal (name)
-
Ordinal (order)
Conclusion: Why Project Teams Should Care?
The million dollar question for project teams is:
"Why are we going to all this trouble to describe
the main project metric?" The most important reason
why teams should fully describe their metrics and
understand what they are improving in their process
is simple: Procedures and methods differ by data
type. Understanding data descriptions is the first
step in a successful Six Sigma deployment.
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