1 As Class Convenes u Find your team u Sign attendance form u Insert any work due today and u Return folder to the front desk

2 Session Agenda u Evaluating Alternatives40 min u Working on Project (review of some notebook work)35 min

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

4 Sample Scoring Table

5 Determining Ratings: The Text Book Says u Use relative comparisons u Use a simple rating scale 1 = much worse than reference to 5 = much better than reference

6 Problems With Relative Rating u 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) u Not rigorous for non experts

7 In Some Cases We Can Do Better u Use absolute instead of relative rating of concepts u Use engineering science to predict the values of the criteria for the concepts

8 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

9 Reference for Today’s Material [1] N. Cross, “Evaluating Alternatives,” in Engineering Design Methods, Chichester, John Wiley and Sons, 1989, pp

10 1. List Design Objectives u Decision requires criteria (objectives) u Includes: –Technical factors –Economic factors –User requirements –Safety requirements –Etc.

11 2. Rank-order Objectives u Individual: Ordered set of note cards to indicate relative importance u Team: pair wise comparison matrix or table

12 Pairwise Comparison ABC A B C

13 Pairwise Comparison ABC A1 B0 C

14 Pairwise Comparison ABC A11 B0 C0

15 Pairwise Comparison ABC A11 B01 C00

16 2. Rank-ordering continued u Order established u The ordering is an ordinal scale u Ordinal scales should not be used in arithmetical operations

17 3. Assign Relative Weightings to Objectives u Use rank ordering to spread out along a 1 to 10 scale u Assign a fixed number of points, say 100) among the objectives u Utilize an Objectives Tree

18 Example Objectives Tree G1 1.0 G G12.25 G13.25 Manufacturing Cost Aesthetically Pleasing Long Lasting G G Cost of Materials Cost of Assembly

19 3. Assign Relative Weightings Continued u The relative weightings are an interval value scale u Interval value scales can be used in arithmetic operations

20 4. Establish Utility Scores for Objectives u Need to convert objectives into things measured (metrics) u Establish a scale to define what is good; what is bad

21 Two Sample Scales 11 Pt Scale Meaning5 Pt ScaleMeaning 0Total useless0Inadequate 1 2Very poor1Weak 3Poor 4Tolerable 5Adequate2Satisfactory 6 7Good3 8Very good 9Excellent4 10Perfect

22 Scale for Car Objectives ScaleFuel Consumption (miles/gal) Comfort 0<27Very uncomfortable 129Poor Comfort 232Below Average Comfort 335Average Comfort 438Above Average Comfort 541Good Comfort 6>43Extremely Comfortable

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26 Calculate Relative Utility Values for Alternatives u Review Figure 62 on handout u Notice untility scores for each concept fragment and each objective (upper left corner, see Notes for meaning) u Which concept(s) is the winner?

27 Comments on Notebook Assessment u None of the Notebooks received at least a Meets for TA5 even though there was evidence of much work being done u Most assessments for IA8 were meets but there were some E’s and a few NI’s

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