Objective tree method

What’s the Objective?
• Objectives (or goals) are expressions of the
desired attributes and behaviors that the
client wants to see in the product
– Objectives are
• ‘Be’ words
• They are qualities the object should have
– Clients tend to speak in terms of objectives
• So, our task today is to uncover the objectives
of a design project

Objectives Tree Method

• The objectives tree method is an approach to transform
vague design statements into more specific customer
requirements
• Make vague statements more specific by asking:
– What is meant by that statement?
• Other useful questions to ask when expanding and
clarifying design objectives:
– Why? How? What?

Objectives Tree Method (2)

• Three step procedure:
1. Prepare a list of design objectives
2. Order the list into sets of higher-level and
lower-level objectives
3. Draw a tree of objectives, showing
hierarchical relationships and
interconnections


Step 1: Listing the Objectives
• This can be done by:
– Talking with (interviewing) your customer
– Thoroughly reading any written design statements
and requirements
– Brainstorming within your team
• Take vague statements and make them
clearer by asking “what is meant by this
statement”


Step 1 (cont.): Culling the Objectives
• After the initial list is compiled, some things other than
objectives may have slipped in
– Constraints - restrictions or limitations on a behavior or some
aspect of a design
– Functions - operations the design is supposed to do
– Implementations - ways to execute the functions
• Check if each statement is an objective
– Objectives are normally “being” statements
• Try saying “an objective is to be [statement] ”
• If it makes sense, then it’s most likely an objective
– Objectives can also be written as “more (or less) of [the statement]
is better than less (or more) of [the statement]”


Step 1 Active Experimentation

• As a team, generate a list of objectives for the bumble ball
toy
– “Experience” the bumble ball
– Ask each other questions about what they want the bumble ball
to do
– Write down the statements and check if they are really objectives


Step 2: Ordering the List
• Group the statements into related topics using
an affinity diagram

Design
Objective
Major objective 1
Second level objective 1.1
Third level objective 1.1.1
Third level objective 1.1.2
Major objective 2
…


Step 2 (cont.): Affinity Diagram
• Copy design objectives to post-it® notes
• Place one on a board
• Compare next objective card to the first
– If different, begin a new column
– If similar intent, place under the first column
• Repeat for all design objective cards
• Result: Objectives sorted by similar statement
– Within each column there may be levels of objectives
• Lower-level objectives answer the question “How?”
• Higher-level objectives answer the question “Why?”
– Transform to a hierarchical list of objectives


Step 3: Draw the Tree
• From Step 2, you have a clustered set of
objectives
– Notice that some of the objectives within a
cluster may be more specific than others
– This implies a hierarchical nature to the
objectives
• The hierarchy (general to more specific)
can be represented in a graphical structure
known as an objectives tree


Step 3: Draw the Tree (2)
• Consider the example objectives list and resulting tree for
the design of a safe ladder:
The ladder should be safe
The ladder should be stable
Stable on floors and smooth surfaces
Stable on relatively level ground
The ladder should be reasonably stiff
The ladder should be marketable
The ladder should be useful
Useful indoors
Useful for electrical work
Useful for maintenance
work
Useful outdoors
Be useful at the right height
The ladder should be relatively inexpensive
The ladder should be portable
Be light weight
Be small when ready for transport


• The Objectives Tree diagram looks like an
“upside-down” tree
– The overall objective of the tree is at the top
– Underneath it, branches break the objective
into more detailed objectives
– Can have many levels and interconnections
As you move deeper into the
hierarchy, the objectives answer
the question “how is the above
objective met?”
As you move higher up in the
hierarchy, the objectives answer
the question “why are the below
objectives important?”


• The objectives
tree diagram
may
alternatively be
drawn on its
side
• Example: Car
door


• What’s wrong with this tree?

Objectives are not
distinct from
higher level (only
one sub-
objective)

Objectives Tree Summary
• Determining a design’s objectives is part of
clarifying the design problem
• An objectives tree is a graphical way to show:
– Your design’s objectives
– The hierarchy of your objectives
• Objectives are “being” words and express the
attributes and behaviors expected by your
client

Objective tree method

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