The best techniques are often the simplest.

Cause and Effect Analysis
What is it?

Cause and effect analysis is a technique which may be used in improvement
projects to identify how different possible causes affect a given problem.
Sometimes referred to as the ‘Ishikawa’ or the ‘Fish Bone’ diagram.

Why use it?
• To help generate ideas and record them.
• To reveal hidden relationships and highlight important relationships.
• To investigate root causes.
When might it be used in projects?
• Cause and effect analysis is an invaluable aid to project management.
• It is a useful aid to problem management in general.
• It is a useful means to getting a quality improvement group working
together in its early history.
Benefits of using cause and effect analysis
• As well as identifying individual causes to problems, groups of causes
can be located that are not immediately obvious.
T&T No: 1
Title: CAUSE AND EFFECT ANALYSIS
For use by: Anyone involved in problem-solving or improvement projects.
When to use: Getting to the root cause of problems.
Also see T&T
No:
8, 13, 24, 40
Difficulty Rating: 2 Category: (A) Find out ‘What’s really going
on?’

• Use of the technique in a group enables everyone to contribute. In this
way, the widest range of expertise can be drawn on.

Developing the cause and effect diagram

1. Establish the effect/problem to be investigated.
2. �� On the flipchart or paper draw a box with the effect/problem
statement in it.
3. Draw a line extending from the left of the box and identify the main
categories of causes (e.g. Manpower, Machinery, Methods,
Materials, or develop categories that suit your business).
4. Draw lines extending from the one attached to the box, one for each
category.
5. Brainstorm (see T&T No 40) for sub-causes in each category and
attach them to the appropriate line. (This can be done using post-its.
Move them as the group considers where the causes should lie.)
7. Once the causes are located, lines expressing relationships between
the causes can be added, usually in a different colour.
�� Ground rules for success
• Use large diagrams.
• Ensure everyone’s participation.
• Examine relationships between causes.
• Do not overload the diagram:
– isolate dominant causes.
– be sure you have defined the problem.
• Do not look for someone to blame.
• Follow brainstorming rules.

Case study: Cause and Effect
An electrical goods distributor was having a significant increase in goods
returned due to inaccurate orders being filled and delivered. This was the
responsibility of the order requisition team and the warehouse picking
teams.
Representatives from all departments, including sales and order
processing, and the warehouse staff were brought together and were helped
to construct a cause and effect diagram.
The effect of increased numbers of returns was caused by many different
factors, including:-
Materials – equipment boxes not clearly labelled.
– shelves too low or too high.
– box stacking unstable, some spillage, etc.
Manpower – shift system resented, resulting in poor motivation.
– lack of measures of productivity.
– lack of cooperation between departments.
– poor supervision.
Machinery – warehouse belt breakdown.
Money – poor incentive scheme.
This exercise resulted in a number of shop floor changes which were owned
and followed through by the staff themselves, resulting in an 80% reduction
in order errors.