# 2010-08-02 toaster slides

```Buying a toaster:
multicriteria decision analysis (MCDA)
in daily life
Defining decision criteria
Family meeting
Price
Number of slots
Evenness of toasting
Defining the scale to capture relative
weights of decision criteria
Use a simple weight elicitation method for ease of use (e.g. scale 1 to 5)
No 0 value as this would nullify consideration of a criteria selected by the family
Criteria
Weights
Low
high
1 2 3 4 5
Evenness of toasting
1 2 3 4 5
Number of slots
1 2 3 4 5
Price
1 2 3 4 5
Defining anchors and toaster scoring scale
for each criteria
Ensure same scale direction for all criteria
0 is used to capture when characteristics of a toaster for a given criteria does
not bring value
Use a small scale for ease of use (e.g. 0 to 3)
Criteria (alphabetical)
Scale and anchors
0 – not available
1
2
Evenness of toasting
0 – very uneven
1
2
3 – uniformly even
Number of slots
0 – 1 slot
1
2
3 – 4 slots
Price
0 – very expensive
1
2
3 - inexpensive
Data collection & synthesis for each
criteria
Decide how many toasters to choose amongst
What is the source of information?
Local store
Consumer association reviews and test results
Technical sheets for each toaster
Experiences of family and friends
Using MCDA tool
Example: Bob’s assessment
1st step - Weighting
How important is each criteria relative to the others (weight)?
(capture personal preferences)
Criteria
Bob’s weights
1 2 3
4 5
Evenness of toasting
1 2
3 4 5
Number of slots
1 2 3 4 5
Price
1 2 3 4 5
Example: Bob’s assessment
2nd step scoring Toaster A
Criteria
Synthesized data
toaster A
Scores
Available, but no data on
(technical sheet)
0 – not available
1
2
Evenness of toasting
Excellent (technical sheet)
Declines after 1 year
(friend)
Number of slots
4
0 – very uneven
1
2
3 – uniformly even
0 – 1 slot
1
2
3 – 4 slots
Price
\$55 (technical sheet)
\$50 (local store)
\$40 + shipping (internet)
0 – very expensive
1
2
3 - inexpensive
Example: Bob’s assessment
Calculating MCDA estimate of Toaster A
Linear model combining normalized weights and scores
Criteria
Weight
Normalized weight
Toaster A
Score Contribution
to estimate
toasting level
4
0.29
1
0.29
Evenness of
toasting
3
0.21
2
0.42
Number of slots
2
0.14
3
0.42
Price
5
0.36
2
0.72
Total
-
1
-
1.85
MCDA estimate for toaster A for Bob: 0.62 (or 62%)
=(1.85/3)*100)
Ranking of options
Calculate average MCDA estimate for whole family
100%
Toaster B
81%
Toaster A
62%
Toaster C
42%
0%
Percent of maximum value
Toaster B best rank according to criteria considered
Contextual criterion!
The kitchen counter is small – only toasters A and C will fit
Toaster A was selected by the family; it will fit on the
counter and it represents better value than C
```