\chapter{Concepts Evaluation}
In the previous chapter we developed a technique to generate different concepts
that satisfies the need statement.  As it was demonstrated the number of 
possibilities that may satisfy the need is a function of the number of entries
(different ways) that fulfill a function.  The larger the number of entries the
larger the number of concepts.  Obviously not all combinations through the
morphological chart will lead to a feasible product.  The goal of this chapter
is to provide a methodology to evaluate the different devices. By the end of
the evaluation process a product which have the highest potential for becoming
the quality product will be identified.   

 With the
availability of the many concepts that were generated by the 
morphological chart.  The difficulty in concept evaluation is that the
designing team must choose which concept to spend time developing when they
still have limited knowledge and data to which they base there selection on.
  Concepts at this time are still abstract, have little details and cannot be
  measured.  Should time be spent refining and adding the little details for
  all concepts then measure the outputs or develop a mechanism to point at one
  concept that most likely become the quality product.  
  
  The screening of concepts can be done using different levels which they are
  \begin{enumerate}
  \item 
  The concepts are directly measured with respect to a fix 
  set of limits (specifications).  If a concept doesn't satisfy the
  specification requirement it will be dropped.
  \item  The design team uses their experience (Engineering gut feeling)
   to eliminate some concepts because the technology is not available
  yet to facilitate the concept or by their judgment the product is not
  feasible.   
  \item  The concepts are evaluated with respect to each other using measures
  defined by the criteria (specifications/wishes).
  This   screening method was developed by Stuart Pugh in 1980s and is often
  called Pugh concept selection.  The purposes of this stage are to narrow the
  number of concepts quickly. 
  \end{enumerate}
  
  \section{Decision Matrix}
 The decision matrix method or Pugh method is based on comparing alternatives
 with the wishes list in the specification table.  An alternative should meet
 the customer demands, otherwise it will be dropped in the initial screening.
 Also the concept should be feasible to the engineering group or it will be
 dropped by the second stage of screening.  The concepts that pass the initial
 two stages need to be evaluated with respect to each other  using a fixed
 criteria (specification table).  The Pugh evaluation 
 method  tests the completeness and understanding of requirements, rapidly
 identifies the strongest alternative and help foster new alternatives.  This
 method is most effective if each member of the design team performs it
 independently and the individual results are then compared.  The results of the
 comparison lead to a repetition of the technique with the iteration continue
 until the team is satisfied with the results.  The Pugh evaluation 
 method is performed using the following steps:
 \begin{enumerate}
 \item {\bf Choose the Comparison Criteria}.  If all alternatives fulfill the
 demands on the same level then the criteria should be the wishes in the
 specification table.  Remember the wishes were organized in an order fashion
 before they were used in the house of quality.  The order is based on the level
 of importance according to the design team.  A weighting factor between 0 and
 10 is assigned by the design team for each wish.  The basis for the weighting
 factor is the engineering team feeling of how important the attribute to the
 final product.
 If the alternatives have differences in the levels at which demands may be
 fulfilled then the demands can be entered in the comparison criteria.
 \item {\bf Select the Alternatives to be Compared}
 From the morphological chart different alternatives will be generated, some of
 these alternatives will be dropped because they do not satisfy the customer
 demands or they are not feasible.  The rest of the alternatives are possible
 candidates.  However by using the initial screening stages few alternatives
 will be left for the final stage.
 
 \item {\bf Generate Scores}.  After careful consideration, the design team
 chooses a concept to become the be benchmark or
 datum against which all other concepts are rated.  The reference is generally
 wither an industry standered or an obvious solution to the problem.  It can be
 commercially available product, an earlier generation of the product, or any one
 of the concepts under consideration or a combination of a subsystems combined to
 represent the best feature of different products.
 
 For each comparison, the concept being evaluated is judged to be either better
 than, about the same as or worse than the datum.  If it is better than the
 datum the concept is given a [+] score.  If it is judged to be about the same as
 the datum the concept is given [0]. If the concept does not meet the criterion
 as well as the datum does, it is given a [-].
 \item {\bf Compute the Total Score} After a concept is compared with the datum
 for each criterion, four scores are generated: The number of plus scores, the
 number of minus scores, the overall total and the weighted total.  The overall
 total is the difference between the number of plus scores and the number of
 minus scores.  The weighted total is the sum of each score multiplied by the
 importance weighing.  
 The scores can be interpreted in a number of ways:
 \begin{itemize}
 \item If a concept or a group of similar concepts has a good overall total
 scores or a high + total score, it is important to notice what strength they
 exhibit, that is which criteria they meet better than the datum.  Likewise the
 grouping of - scores will show which requirements are hard to meet.
 \item If most concepts get the same score on a certain criterion, examine that
 criterion closely.  It may be necessary to develop  more knowledge in the area
 of the criterion to generate better concepts.  Or it may be that the criterion
 is ambiguous, or interpreted differently by different members of the team.
 \item To learn even more, redo the comparison , with the highest scoring
 concept used as the new datum.  This iteration should be redone until a
 clearly "best" concept or concepts emerge.
 \end{itemize}
 
 After each team member has completed this procedure, the entire team should
 compare their individual results.  Then a team evaluation need to be conducted.
 \end{enumerate}
 \section{Example}
 In designing a splashgard for a mountain bicycle the design team generated the
 following function diagram
 \begin{figure}
 \vspace{3in}
 \caption{Function diagram for Splashgard}
 \end{figure}
 
 The preliminary list of customer requirement   of the splashgard are shown in the following table
 \begin{figure}
 \vspace{5in}
 \caption{ Preliminary List of Customer Requirement for Splashgard}
 \end{figure}
 The The morphological chart is shown in the following diagram
 \begin{figure}
 \vspace{5in}
 \caption{Morphological Chart for the Splashgard}
 \end{figure}
 From the morphological chart the following concepts where generated
 \begin{figure}
 \vspace{5in}
 \caption{Concepts Sketch}
 \end{figure}
 The decision matrix is evaluated with respect to concept VII as the datum
 \begin{figure}
 \vspace{5in}
 \caption{Initial decision Matrix for Splashgard water deflection Subsystem}
 \end{figure}

\section{Example:Automatic can crusher}
From the morphological chart many possible combinations of devices can be obtained, but not all
of these processes are good or able to be effectively accomplished.  In this stage the deign
team begins to limit the possible deignes based on specifications, manufacturability, cost and
other factors.  The surviving designes are then evalusted againes each other.  A decision
matrix is constructed to evaluate the designes against the wishes obtained from the
specification table.  Specifications are weighted by the importance with one being the lowest
and ten being highest importance.  The concepts are evaluated and one deisgn was choosen by the
design team to be thethe best possible design, this design is considered the  datum by which all
of the other deisgnes are compared. Then all of the other designes are evaluated against the
datum by "+" if they are exceed datum in a wish, a "-" if they are below datum in the wish and
"0" if they are equal to the datum in teh wish.  Results are tallied and scores are evelauted,
then the best one of the designs is placed as datum and the evaluation is done again.  The
highest scored design was the choosen design to be built.
\begin{figure}[ht]
\vspace{8in}
\caption{Evaluation of designes:V is datum}
\end{figure}
\begin{figure}
\vspace{8in}
\caption{Evaluation of designes:IV is datum}
\end{figure}
