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The Pugh method is a decision support tool. It allows us to choose between different alternatives optimally by applying several criteria simultaneously.

Introduction

The Pugh Method is a decision support tool. It allows us to choose optimally between various possible alternatives by applying several criteria simultaneously. It could apply for example to choose between various possible designs, various opportunities for improvement or between various manufacturing technologies.

The principle

The method was invented in the 1980s by Stuart PUGH, professor of design at Strathclyde University in Glasgow. The interest of the method is based on comparative evaluation against an identified basis, which allows a more precise and simpler evaluation..

The method

1 – Identify the evaluation criteria

The first step is to define the different criteria that will enable us to evaluate the best alternative (s). To be exhaustive, it is necessary to do this research in groups of 4 to 8 people of different services.

2 – Identify a basic solution of evaluation

We will evaluate each of the alternatives against a standard level. We will rely on an existing product, an existing technologist … which is closest to our case. Depending on the ambition of the project, we will choose a comparison via a level “average” or via the best known to date if we want to aim better.

3 – Conduct the evaluation (- ; 0 ; +)

For each of the criteria and for each alternative, the question is: is this alternative better or worse than my baseline ?

We perform a notation with + and – :

  • + : the alternative is better than the basis of comparison for the criterion in question.
  • – :  the alternative is worse than the basis of comparison for the criterion in question.

 

In the case where there are more than 5, we will use a wider scale of evaluations: -, -, 0, +, ++ for example.

4 – Analyze

Once the evaluation is done, we will count the number of +, – and 0. Then we will calculate the number of + and the number of less to select the best solution..

In the example below, alternative 3 is the best.

Standard of comparison

Alternative 1

Alternative 2

Alternative 3

Alternative 4

Criterion 1

0

+

0

+

Criterion 2

0

0

+

+

Criterion 3

0

0

0

+

Criterion 4

0

+ +

Sum of +

0

1

1

4

1

Sum of –

0

2

0

0

3

Sum of 0

0

1

3

0

0

Sum of + minus Sum of –

0

-1

1

4

-2

5 – Refine and make a decision

If in the first round a winner is not clearly identified, 2 solutions are possible :

  • Iterate : we will analyze the weak points of the alternatives and see how, by relying on the alternatives having obtained a +, we can transform them into +. This by combining them for example. It is therefore iterated on each of the criteria and re-evaluated each time until a winner appear.
  • Weighting : some of the criteria are more important than others. We can weight them and redo the evaluation. For example, with a weight of 5, a + + will actually be worth +++++. This weighting will be done using the principles of Voice Of Customer.

Source

S. Pugh (1991) – Total design

S. Pugh (1996) – Creative innovative products using total design: the lig-ving legacy of Stuart Pugh

S. Chowdhury (2002) – Design For Six Sigma,

S. E. Burge (2006) – Matrix diagram from the systems thinking tool box

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