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thebenshimagroup © 2008 John Gershenson, Ph.D. 07. Pugh Evaluation

Phase A: Design Problem Analysis

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  Pugh Evaluation –  A chart showing the quantitative reasoning behind

the selection of the final concept(s) accompanied by a brief description of the selection process and a detailed description of the final concept(s).

  System Requirements Review –  A review conducted during the concept

development phase to ensure that the requirements and the selected concept will satisfy the project.


 Need equivalent set of concepts first  Abstract, not detailed, unmeasurable  Need to find right measure  Absolute vs. relative  Decision Matrix  Feasibility judgment, technology

readiness, go/no-go screening

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 Gut feel by designer  Not feasible, conditionally feasible, or

possibly feasible


 Good write up of concept  Compare each remaining concept

alternative to the customer requirements in QFD

 Eliminate any concept with too many no-go’s

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 Why not base it on customers, based design on them?

 Relative


(NASA Systems Engineering Handbook, SP 2007)

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(Lumsdaine et al., 2006)


 Finding a “best” design

 Prevents a team from “falling in love” with a flawed design or one not meeting all design constraints or objectives

 Communication tool; builds consensus

 Based on the “voice of the customer”

 Results in significant cost savings (Lumsdaine et al., 2006)

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  Discussions reveal arbitrary criteria –  Team members gain insight into the problem and clearly

understand the criteria which become increasingly better defined   The discussion also leads to creative leaps between different

concepts and idea synthesis, as flaws are attacked together and the team experiences synergy –  This process generates new concepts that are added to the

evaluation matrix –  The resulting new concepts are better than the original ideas –  No flaws are overlooked; engineering changes are eliminated, and

invulnerable products are developed that will succeed in the marketplace

  The team develops consensus about the best concept



  A “best” conventional design is chosen as datum against which the new concepts are compared –  If no benchmark exists, one of the new concepts is

arbitrarily chosen as the initial datum   For subsequent rounds, the best concept from

the previous round is chosen as the new datum –  All design concepts must be improved to be able to

compete or survive in the new rounds (Lumsdaine et al., 2006)

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  This process is repeated several times over days or weeks/months, until a superior concept emerges that cannot be overturned since all negatives (“flaws”) have been removed


 For a valid evaluation, the list must be explicit, relevant, comprehensive, and include performance specifications and constraints

  In the early conceptual stages, do not use tight constraints or too many details


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  Begin with the Requirements and Objectives in the Project Analysis Statement

  Criteria will grow more specific, detailed, and refined in subsequent evaluation rounds

  Make sure the criteria involve the “voice of the customer”

  Also consider quality, manufacturability, low cost, and environmental impact in the criteria



  They are outline solutions to the design problem, where rough sizes and structural relationships among major parts are given

  This phase places the greatest demands on designers for creative thinking, and innovation can originate here

  Decisions are made on how each major function will be performed—but consider many alternatives of how this could be achieved


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 Conceptual designs are worked out in some detail to allow estimates of cost, weight, overall dimensions, and assessment of feasibility

 Each initial concept should be worked out to about the same level of detail and format, to allow fair evaluation



 The Design teams brainstorm and rank a list of 15 to 20 evaluation criteria – Based on customer needs and design

objectives  The best existing product is chosen as

the benchmark or datum


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 The matrix is prepared on a large paper or wallboard – Column1: List of criteria – Column2: Datum – Design concepts are posted at the top of

the next columns have additional columns available for new concepts generated during the evaluation



  Each design concept is presented by its champion and then discussed and evaluated by the team against the list of criteria and the datum

  If new ideas come up during this process, they are entered on the matrix as a new concept

  The results of the matrix are evaluated –  The datum for the next round is chosen, and

criteria are clarified as needed to make them more useful (Lumsdaine et al., 2006)

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  The designers now work to strengthen the positives and remove the negatives of their concepts through synthesis and new ideas, for evaluation in Round 2

  The evaluation and improvement process is continued for one or more rounds, with the strongest concept chosen as the datum each time



  Takes place in Phase B   Over a period of time, teams further develop

their best concepts, run analyses, and research missing information –  The designs/concepts are now engineered or

developed to more detail   Weaker designs/ideas are dropped (after their

good points have been judged for use elsewhere)


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 The matrix and the process of concept improvement are iterated until a winning concept emerges, all team members understand why this solution is best, and all are committed to this concept which is now ready for prototyping



  The datum for a new round must be the best concept from the previous round -the one with the largest number of positives, not the one with the lowest negatives

  Do not forget to improve the datum for the next round; make it an even better concept by trying to eliminate all its weak points

  The overall aim must always be to try to eliminate all negatives (the weaknesses or flaws) in the higher-ranking concepts. Do not be too quick to accept shortcomings in your concepts without some very good reasons


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I.D. #, Rating Type Fixture Location Switching

A 3, 20 watt 2-ft fluorescent, triangular under wall cabinets individual

B 4, 40 watt 4-ft fluorescent tube on top of cabinets 3-way switch

C 2, 75 watt aluminum spotlight 5 ft above sink individual

D 1, 20 watt 2-ft fluorescent tube under microwave plug-in cord

Existing Kitchen Lighting Fixtures


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  Improve the general and task lighting in the kitchen while upgrading the lamp quality and matching or complementing the fixture style in the adjacent dining and living rooms, at reasonable cost and without remodeling the kitchen or covering the beauty of the paneled ceiling.


1 Track Lighting Install an 8-ft long track with 4 movable spots (50 watt each, black) to match existing track light in adjacent living room. Plug into outlet over cabinet near sink.

2 Sink Task Lighting Replace the two spotlights over the sink with new, nicer-looking, and more efficient practical lamps.

3 Over-Cabinet Strip Lighting Replace the fluorescent tubes with a lighted strip along the top of all wall cabinets.

4 Fluorescent Hanging Fixtures Install two 4-ft fluorescent fixtures with efficient diffusers at 8-ft level (from chains, with wood surrounds) to replace the over-the-cabinet tubes; wire to main switch. Option explored with supplier.

5 Halogen Fixtures Install two hanging halogen down lights; wire to main switch; match chrome style of under-cabinet triangular fixtures. Option explored with supplier.

6 Brighter Surfaces Paint walls white; install white vinyl flooring; install new white countertop; paint cherry panels in ceiling while.

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# Criteria Now 1 2 3 4 5 6 1 Adequate sink task lighting S + ― + + ― 2 Other countertop lighting ― S ― + + ― 3 General lighting S S S + + + 4 Light to ceiling ― S + ― ― + 5 Energy efficient ― + ― + + + 6 Easy to clean + S S S + ― 7 Easy bulb replacement + S ― S + S 8 Allow deletion of tubes ― ― + ― ― ― 9 Matching adjacent room fixture + + ― ― ― S

10 Attractive high-tech look + + + + + S 11 Low installation labor cost ― + + ― ― ― 12 Low materials cost ― ― ― ― ― ―

TOTAL POSITIVES (+) 4 5 4 5 7 3 TOTAL NEGATIVES (―) 6 2 6 5 5 6


  None of the concepts provided a complete and satisfactory solution

  More options are needed.   Concept #5 is chosen as the

new datum   The other concepts are modified

and synthesized, and a new concept is added after discussion with the supplier (#7)

  Concept #6 (painting) is dropped since it does not meet the constraints

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5 Halogen Fixtures Install two hanging halogen down lights; wire to main switch; match chrome style of under-cabinet fixtures (DATUM).

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Fluorescent Track Lighting Install a black 8-ft long, 2-circuit track with 3 movable cans (150 watt incandescent bulbs or fluorescent bulb option) and one black 2-ft fluorescent, 40 watt movable parabolic louvered diffuser to match living room track light. Mount to bottom of beam; connect to main switches with conduit along beam edge.

8 Sink Task Lighting Replace two spotlights over the sink with black cans matching the track lights of Option #7. Use fluorescent bulbs.

9 Over-Cabinet Strip Lighting Replace the fluorescent tubes with a rope light along the top of all wall cabinets.

10 Fluorescent Hanging Fixtures Install two 4-ft fluorescent fixtures with efficient diffusers at 8-ft level (sleek high-tech design); hang from ceiling, centered between counters.

11 Halogen Fixtures Install two hanging halogen down lights; wire to main switch; match style of dining room chandelier, if possible.


# Criteria 5 7 8 9 10 11

1 Adequate sink task light S + ― S S

2 Countertop lighting (window wall) + + ― S S

3 Countertop lighting (stove wall) + ― ― S S

4 Ceiling illumination S S + S S

5 Low-energy night lighting S + + S S

6 Low glare + + + + S

7 Flexible (direction, additions, lumens) + + ― S S

8 Easy bulb replacement S S ― ― S

9 Energy efficient S S ― S S

10 Easy to clean S S ― S S

11 Preserves view of ceiling/open space S + + ― S

12 Allows deletion of cabinet-top tubes + ― + S S

13 Matching adjacent room lamp styles + + S ― +

14 Attractive to future owners + + ― ― S

15 Low labor cost S + + S S

16 Low materials cost ― + ― + S

TOTAL POSITIVES ( + ) 6 10 6 2 1

TOTAL NEGATIVES (―) 2 2 9 4 0

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  Concepts #9 and #10 are eliminated (#9 does not provide sufficient light to help solve the basic problem; #10 obstructs the daytime view of the paneled ceiling)

  Concepts #7 and #8 are combined into new Concept #12

  Since the customer was not familiar with the “wall washer” fixture, the supplier suggested she see one in use at the MTU bookstore (she especially liked the warm quality and brightness of the light)

  Concept #11 (which had no negatives) is carried forward unchanged


8 Sink Task Lighting Replace two spotlights over the sink with black cans matching the track lights of Option #7. Use fluorescent bulbs.

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Fluorescent Track Lighting System Install a black 8-ft long, 2-circuit track with 3 movable cans with fluorescent bulbs and two 2-ft fluorescent, 40-watt movable parabolic louvered diffusers (“wall washers”). Mount to bottom of beam; connect to main switches with conduit along beam/ceiling edge. Replace the two spotlights over the sink with matching cans and fluorescent bulbs to achieve a flexible, attractive, and easily modified, adjustable lighting system.

11 Halogen Fixtures Install two hanging halogen down lights; wire to main switch; match style of dining room chandelier, if possible.

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Criteria 12 11 1 Adequate sink task light + ―

2 Countertop lighting (window wall) + ―

3 Countertop lighting (stove wall) + ―

4 Indirect lighting to ceiling (eliminate cave look) + S

5 Low-energy night lighting + ―

6 Low glare, especially for eye-glass wearers + ―

7 Flexible in direction, light level, future additions + ―

8,9 Easy bulb replacement; easy to clean of grease buildup S,S S.S

10 Energy efficient, cool burning (safety concern) S ―

11 Sun-type lighting quality + +

12 Preserves view of beautiful paneled ceiling S ―

13 Allows deletion of all plugged-in tubes S ―

14 Matching adjoining living and dining room light fixtures + S

15 Attractive to future owners; good “selling” point S ―

16 Reasonable installation costs + S

17 Material cost in line with “value added” S S

TOTAL POSITIVES ( + ) 10 1

TOTAL NEGATIVES (―) 0 10


 Concept #12 is shown to be superior (no negatives); it solves the original problem with added value (flexibility and lighting that exceed the customer’s expectations)

 Round 3 confirmed the superiority of combining Concepts #7 and #8 (with further improvements), it overcame the two serious flaws of Concept #8

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 Concept #11 (without negatives in Round 2) now rated very poorly against the high-quality datum of Round 3. Also, the “hot” halogen bulb is a safety concern

 Note how the list of criteria became more “demanding” in each round

 The total cost of $742 was acceptable to get such a functional, flexible, as well as attractive system


  The Pugh method was crucial for clarifying criteria, generating options, and identifying the optimal solution (with input from the supplier and research by the customer)

  The best solution did not emerge until Round 3   The customer is very pleased with the new lighting,

both initially and over time, and the system was an enhancement that helped sell the house

  The slight delay in start-up of the wall washers has not proved to be annoying, since the spots respond immediately when the switch is operated; on the contrary, the two-stage sequence increases appreciation for the bright, warm light supplied by the wall washers

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  From www.InnovationToday.biz –  PUBLICATIONS / TEACHING AIDS /

Pugh Method Example   Although this only shows Round 1, the

discussion brings out some important points and features of the Pugh method



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 What? –  It examines the functional and performance

requirements defined for the system and the preliminary program or project plan and ensures that the requirements and the selected concept will satisfy the project

 When? – This review is conducted during the

concept development phase (NASA Systems Engineering Handbook, SP 2007)

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 Results –  Successful completion of the System

Requirements Review freezes program/project requirements and leads to a formal decision by the cognizant program administrator to proceed with the proposal request preparation for project implementation



  Entrance criteria –  Successful completion of the Project Concept

Review in Pre-Phase A –  A preliminary SRR agenda and success criteria –  Following technical products are available to the

cognizant participants   System requirements document   Risk management plan   Updated cost estimate   Concept sketches


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  Success Criteria –  The project utilizes a sound process for the allocation and

control of requirements throughout all levels, and a plan has been defined to complete the definition activity within schedule constraints

–  Requirements definition is complete with respect to top-level project requirements

–  Requirements allocation and flowdown of key driving requirements have been defined down to subsystems

–  Preliminary approaches have been determined for how requirements will be verified and validated down to the subsystem level

–  Major risks have been identified and technically assessed, and viable mitigation strategies have been defined

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