7.2.2 CAUSE AND EFFECT DIAGRAM

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The Cause and Effect Diagram shown in Figure 7-1 is used to create multiple

pathways to find causes and then reasons for the causes that contribute to a

problem.

The cause and effect process is a logical process and has been around for a

long time. Cause and effect analysis is an effective tool that allows people to

easily see the relationship between factors to study processes and situations and

to use them for planning.

The Cause and Effect diagram is also called the Ishikawa Diagram (after its

creator, Kaoru Ishikawa of Japan), or the Fishbone Diagram (due to its shape).

F i g u r e 7 - 1 — F i s h b o n e D i a g r a m

Cause Cause

Cause Cause Cause

Reason

Reason

Effect

The Cause(s) in the diagram would be major contributors to the program or

project such as Processes, People, Machinery, Materials, and Environment. You

will need to adjust these Causes to fit your situation. In some cases, for instance,

you may want to use elements of the organization as Causes. In other cases, you

may want to use elements of your specific process as Causes. The Causes for

your program could be similar to these but not necessarily the same. The Reasons

are why the Cause is contributing to the problem. For instance, Reasons

that contribute to Materials Cause could be: 1) The wrong materials were specified

or 2) the SOW was incorrect or 3) the subcontractor or vendor did not

perform properly. These Reasons will go on and on, and they will be specific to

your project and to the product you are creating. Process Reasons could be an

incorrect process that falls short of specifying some critical action necessary for

this project. And so on.

Some time later, a modification to the classical fishbone diagram was created

to make it into what is called a ‘‘Tree Diagram.’’ A drawing of the Tree Diagram

can be seen in Figure 7-2. If you use a drawing program to support your ‘‘Cause

and Effect’’ analysis, your end product will resemble that figure.

An even simpler method than drawing the flow is to use a spreadsheet program

to create an ordering of ‘‘Reasons,’’ ‘‘Causes,’’ and ‘‘Effects.’’ For purposes

of organization, the presentation is reversed: the Effect is on the left, the Cause

in the middle, and the Reason on the right, as they appear in Table 7-2. The

Effects are numbered as 1, 2, 3, and so on. The Causes are numbered 1a, 1b,

and 2a, 2b, and so on. The reasons are numbered 1.a.1, 1.a.2, and 2.a.1, 2.a.2,

and so on. Using this technique, you can develop your Causes and Reasons in

a nonlinear or random fashion, so long as you maintain the relationships. A

simple ‘‘sort’’ will place the Reasons, Causes, and Effects in their proper places.

F i g u r e 7 - 2 — T r e e D i a g r a m

Reason

Reason

Reason

Reason

Reason

Reason

Cause

Cause

Cause

Effect

T a b l e 7 - 2 — C a u s e a n d E f f e c t T a b l e

Sequence Effect Cause Reason

1 XXXXXXX

1a YYYYYYYY

1a1 ZZZZZZZZZZ

1a2 ZZZZZZZZZZ

1a3 ZZZZZZZZZZ

1b YYYYYYYY

1b1 ZZZZZZZZZZ

1b2 ZZZZZZZZZZ

1b3 ZZZZZZZZZZ

1b4 ZZZZZZZZZZ

1c YYYYYYYY

1c1 ZZZZZZZZZZ

1c2 ZZZZZZZZZZ

You can also use three columns of data and one column of sequencing as shown

in Table 7-2. If necessary, another column can be added.

The Cause and Effect Diagram is used for listing the primary, secondary, and

even tertiary causes that relate to some selected problem area and provides a

visual display of a list in which you identify and organize possible causes of

problems, or factors needed to ensure success of some effort. It was created so

that all possible causes of a result could be listed in such a way as to allow a

user to graphically show these possible causes. From this diagram, the user can

define the most likely causes of a result. This diagram was adopted by Dr. W.

Edwards Deming as a helpful tool in improving quality. Dr. Deming has taught

Total Quality Management in Japan since World War II. He has also helped

develop statistical tools to be used for the census and taught the military his

methods of quality management. Both Ishikawa and Deming use the Fishbone

Diagram as one of the first tools in the quality management process.

One limitation of the Cause and Effect Diagram, whatever presentation technique

is used, is that the diagram does not show magnitude. One might say that

it is ‘‘a good map but it lacks time and distance data.’’2 Data Sheets, Histograms,

Pareto Analysis, Failure Mode Effect Analysis (FMEA), and other data collection

and analysis tools can be used to quantify the data.

For additional information on the Cause and Effect Process, see:

John F. Early, ed. Quality Improvement Tools. Wilton, Conn.: Juran Institute,

1989.

P.E. Plsek. ‘‘Tutorial: Management and Planning Tools of TQM.’’ Quality

Management in Health Care 1, no.3 (1993).

Peter Senge. The Fifth Discipline. New York: Doubleday, 1990.

Software used to support the Cause and Effect Process is listed in Table 7-3.

T a b l e 7 - 3 — C a u s e a n d E f f e c t S o f t w a r e

Tool Product Vendor

Cause and Effect

‘‘REASON 4’’ DECISION Systems, Inc.

‘‘Flowcharting Cause & Effect Module’’ for ‘‘Six Sigma

Software Suite’’ Quality America, Inc.

‘‘Root Cause Analysis (RCA)’’ Root Cause Analyst

‘‘PathMaker’’ SkyMark

Following is contact information for the companies listed in Table 7-3:

DECISION Systems, Inc.

802 N. High St. Ste. C

Longview, TX 75601

Phone: 903-236-9973

Fax: 903-236-3794

Web site: www.rootcause.com/

E-Mail: dsi@rootcause.com

Quality America, Inc.

P.O. Box 18896

Tucson, AZ 85731-8896

Order: 800-643-9889

Phone: 520-722-6154

Fax: 520-722-6705

Web site: www.qualityamerica.com/

E-mail: sales@qualityamerica.com

Root Cause Analyst

Orion Healthcare Technology

1823 Harney Street, Suite 101

Omaha, NE 68102

Phone: 800-324-7966

Fax: 402-341-8911

Web site: www.rcasoftware.com/

E-mail: info@casoftware.com

SkyMark

7300 Penn Avenue,

Pittsburgh, PA 15208

Phone: 800-826-7284

Fax: 412-371-0681

Web site: www.skymark.com

E-mail: info@skymark.com