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Chapter 2

How People make DecisionsInvolving

Multiple Objectives

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Examples of decisions involving multiple objectives

Choosing a holiday liveliest nightlife least crowded beaches most sunshine most modern hotels lowest cost

Choosing a company to supply goods best after-sales service fastest delivery time lowest prices best reputation for reliability

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Bounded rationality The limitations of the human mind

mean that people use ‘approximate methods’ to deal with most decision problems

As a result they seek to identify satisfactory, rather than optimal, courses of action

These approximate methods, or rules of thumb, are often referred to as ‘heuristics’

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Heuristics

These heuristics are often well adapted to the structure of people’s knowledge of the environment

Quick ways of making decisions, which people use, especially when time is limited, have been referred to as ‘fast and frugal heuristics’

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Compensatory vs. non- compensatory strategies

Compensatory strategy - poor performance on some attributes is compensated by good performance on others

- Not the case in a non-compensatory strategy Compensatory strategies involve more

cognitive effort

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The recognition heuristic

Used where people have to choose between two options

If one is recognized and the other is not, the recognized option is chosen

Works well in environments where quality is associated with ease of recognition

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It may be that a more easily recognized manufacturer is likely to have been trading for longer and be larger. Its long-term survival and size may be evidence of its ability to produce quality products and to maintain its reputation.

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The minimalist strategy First apply recognition heuristic If neither option is recognized, simply guess

which is the best option If both options are recognized, pick at

random one of the attributes of the two options and choose best performer on this attribute

If both perform equally well on this attribute, pick a 2nd attribute at random, and so on

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Take the last

Same as minimalist heuristic except that people use the attribute that enabled them to choose last time when they had a similar choice

If both options are equally good on this attribute, choose the attribute that worked the time before, and so on

If none of the previously used attributes works, a random attribute will be tried

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The lexicographic strategy

Used where attributes can be ranked in order of importance

Involves identifying most important attribute and selecting the option which is best on that attribute (e.g. choose cheapest option)

In there’s a ‘tie’ on the most important attribute, choose the option which performs best on the 2nd most important attribute, and so on

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This ordering of preferences is analogous to the way in which words are ordered in a dictionary

the lexicographic strategy involves little information processing (i.e. it is cognitively simple) if there are few ties.

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However, when more information is available, the decision will be based on only a small part of the available data. In addition, the strategy is non-compensatory.

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The semi-lexicographic strategy 

Like the lexicographic strategy - except if options have similar performance on an attribute they are considered to be tied and moves on to the next attribute

It can lead to violation of transitivity axiom…

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Example… ‘If the price difference between

brands is less than 50 cents choose the higher quality product, otherwise choose the cheaper brand.’

Brand Price QualityA $3.00 LowB $3.60 HighC $3.40 Medium

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Elimination by aspects (EBA)

Most important attribute is identified and a performance cut-off point is established

Any alternative falling below this point is eliminated

The process continues with 2nd most important attribute, and so on

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Strengths & limitations of EBA

Easy to apply Involves no complicated

computations Easy to explain and justify to others Fails to ensure that the alternatives

retained are superior to those which are eliminated - this arises because the strategy is non-compensatory.

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In the example, one of the cars might have been rejected because it was slightly below the 1600cc cut off value. Yet its price, service history and mileage were all preferable to the car you purchased. These strengths would have more than compensated for this one weakness.

The decision maker's focus is thus on a single attribute at a time rather than possible trade-offs between attributes.

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Sequential decision making: Satisficing

Used where alternatives become available sequentially

Search process stops when an alternative is found which is satisfactory in that its attributes’ performances all exceed aspiration levels

These aspiration levels themselves adjust gradually in the light of alternatives already examined

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Decision makers use an approach called satisficing.

The key aspect of satisficing is the aspiration level of the decision maker which characterizes whether a choice alternative is acceptable or not .

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In a satisficing model, search terminates when the best offer exceeds an aspiration level that itself adjusts gradually to the value of the offers so far received ...

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Note that satisficing is yet another example of a non-compensatory strategy.

The final choice depends on the order on which the alternatives present themselves.

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Reason-based choice

Shafir et al.:

‘when faced with the need to choose, decision makers often seek and construct reasons in order to resolve the conflict and justify their choice to themselves and to others’.

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Some consequences of reason-based choice it can make the decision maker highly

sensitive to the way a decision is framed.

Decisions framed as ‘choose which to select…’ can lead to different choices to those framed as ‘choose which to reject’

Options can be rejected if they have weakly favorable or irrelevant attributes

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Positive features are weighted more highly when selecting and negative features more highly when rejecting. This violates a basic principle of rational deci sion making that choice should be invariant to the way the decision is framed.

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Example of reason-based choice

Candidate A Candidate BAverage written communication skills Excellent written

communication skills

Satisfactory absenteeism record Very good absenteeism record

Average computer skills Excellent computer skills

Reasonable interpersonal skills Awkward when dealing with

others

Average level of numeracy Poor level of numeracy

Average telephone skills Poor telephone skills

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Factors that affect how people

make choices Time available to make decision Effort that a given strategy will involve Decision maker’s knowledge about the

environment Importance of making an accurate decision Whether or not the choice has to be justified

to others Desire to minimize conflict (e.g. conflicts

between the pros and cons of the alternatives)