As Class Convenes

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As Class Convenes

• Find your team
• Sign attendance form
• Insert any work due today and
• Return folder to the front desk

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Session Agenda

• Evaluating Alternatives 40 min
• Working on Project(review of somenotebook
  work) 35 min

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Learning Objective

• Achieve awareness of the differences between
  Relative Ratings and Absolute Ratings in
  completing Scoring Tables (Matrices)

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Sample Scoring Table
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Determining Ratings The Text Book Says

• Use relative comparisons
• Use a simple rating scale
• 1 much worse than reference
• to
• 5 much better than reference

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Problems With Relative Rating

• Scale Compression
• if reference concept is the best relative to
  criterion 1, what rating values are available for
  criterion 1?
• only 1 (much worse), 2 (worse) maybe 3 (same)
• Not rigorous for non experts

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In Some Cases We Can Do Better

• Use absolute instead of relative rating of
  concepts
• Use engineering science to predict the values of
  the criteria for the concepts

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The Weighted Objectives Method 1

• List Design Objectives
• Rank-order the list
• Assign Relative weights to objectives
• Establish performance parameters or utility
  scores for each objective
• Calculate relative utility values for alternatives

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Reference for Todays Material

• 1 N. Cross, Evaluating Alternatives, in
  Engineering Design Methods, Chichester, John
  Wiley and Sons, 1989, pp. 101-121.

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1. List Design Objectives

• Decision requires criteria (objectives)
• Includes
• Technical factors
• Economic factors
• User requirements
• Safety requirements
• Etc.

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2. Rank-order Objectives

• Individual Ordered set of note cards to
  indicate relative importance
• Team pair wise comparison matrix or table

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Pairwise Comparison
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Pairwise Comparison
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Pairwise Comparison
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Pairwise Comparison
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2. Rank-ordering continued

• Order established
• The ordering is an ordinal scale
• Ordinal scales should not be used in arithmetical
  operations

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3. Assign Relative Weightings to Objectives

• Use rank ordering to spread out along a 1 to 10
  scale
• Assign a fixed number of points, say 100) among
  the objectives
• Utilize an Objectives Tree

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Example Objectives Tree
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3. Assign Relative Weightings Continued

• The relative weightings are an interval value
  scale
• Interval value scales can be used in arithmetic
  operations

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4. Establish Utility Scores for Objectives

• Need to convert objectives into things measured
  (metrics)
• Establish a scale to define what is good what is
  bad

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Two Sample Scales
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Scale for Car Objectives
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Calculate Relative Utility Values for Alternatives

• Review Figure 62 on handout
• Notice untility scores for each concept fragment
  and each objective (upper left corner, see Notes
  for meaning)
• Which concept(s) is the winner?

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Comments on Notebook Assessment

• None of the Notebooks received at least a Meets
  for TA5 even though there was evidence of much
  work being done
• Most assessments for IA8 were meets but there
  were some Es and a few NIs

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Notebook Assessment Continued

• The notebook work (TA5 IA8) is the one body of
  work that can be reassessed as M or E independent
  of the first assessment
• I will log in the best assessment received for
  TA5 and IA8