ECON30019 Chap.13 Bundling, Mental Accounting and Realized Losses
Bundling, Mental Accounting and Realized Losses
Bundling, also called hedonic editing, is the decision to treat two outcomes as one event or as two, and the subject frames it as a choice between integrating and segregating.
Under the standard model the packaging is invisible, because a utility function ranges over total endowments and the same total produces the same utility however it is described, so any effect of bundling is a violation before direction is even discussed.
Four rules follow from the shape of the value function rather than from four separate assumptions: segregate gains, integrate losses, cancel a small loss into a large gain, and detach a small gain from a large loss.
The chapter then widens to mental accounting, which describes how individuals code, categorise and evaluate events, and closes with the disposition effect and the difference between a loss that has been realized and one that is still on paper.
What this chapter covers
- 01
Integrate or segregate, and the standard benchmark that ignores the choice
- 02
The four editing rules, written as inequalities in the right direction
- 03
Why the loss inequality points the way it does
- 04
Deriving all four rules from concavity, convexity and the kink
- 05
Mental accounting, and its three components
- 06
Fungibility, and the claim that gives the framework policy content
- 07
Broad and narrow bracketing
- 08
Booking and posting, and why small routine expenses go unnoticed
- 09
The disposition effect, and the opposite prediction of standard models
- 10
Realized against paper losses, and an endogenous reference point
Design the communication
- 1Classify the two refunds as gains, and note that the gain branch is concave so value per unit falls as the total rises.
- 1Apply the rule: segregate them and send two notices, since two separate credits are valued more than one credit of 130.
- 1Classify the network charge as a small loss beside a large gain, and apply cancellation by folding it into the larger refund as a net credit.
- 1Give the reason: evaluated separately it would land on the steep part of the loss branch near the origin, where the kink amplifies it.
- 1Classify the price rise as a large loss and integrate it with any other bad news this quarter, since the convex loss branch means a second separate loss is evaluated from the reference point again.
- 1Add the mirror case: any small goodwill credit offered alongside the price rise should be sent separately, by the silver lining rule.
Key terms
- Hedonic editing
- The process of categorising outcomes as gains or losses and choosing whether to combine them, which allows people to influence how an event is experienced.
- Integrate
- To treat two outcomes as a single combined event, which is the recommended handling for two losses and for a small loss beside a large gain.
- Segregate
- To treat two outcomes as separate events, which is the recommended handling for two gains and for a small gain beside a large loss.
- Mental accounting
- A description of how individuals code, categorise and evaluate events, assigning them to accounts that are opened, evaluated at some frequency, and closed.
- Fungibility
- The economic property that a unit of money is a perfect substitute for any other. Mental accounting violates it, since money in one account is not fully interchangeable with money in another.
- Disposition effect
- The tendency to hold positions that have fallen in value and to sell positions that have risen, which is the opposite of what standard models predict under some assumptions.
- Realized loss
- A loss made concrete by transferring value between accounts, as against a paper loss that has not been realized. Only the first forces the reference point to update.
Bundling, Mental Accounting and Realized Losses FAQ
Why is the loss rule an inequality with a less-than sign?
Because both sides are negative. The source states that the sum of the separately evaluated losses is less than the value of the combined loss, and since these values are negative, less than means more negative, that is, it hurts more. So the recommendation is to integrate losses. Writing the inequality with a greater-than sign, as students do when thinking about magnitudes, reverses the recommendation.
Do I need to memorise all four rules separately?
No, and you should not. All four are consequences of one curve. Ask which branch each outcome sits on and whether that branch is flattening or steepening as you move from the reference point. A flattening branch means early units are worth more, so splitting adds value; a steepening branch means the reverse. Those two questions reproduce every rule.
Why do realized and paper losses lead to opposite behaviour?
Because only one of them moves the reference point. Realizing a loss forces the reference point to update downward, so the next decision starts near the new position and the person is observed to avoid risk. A paper loss leaves the reference point where it was, so the next decision is still in the loss domain where the value function is convex, and greater risk taking follows.
Exam move
Do not learn the four rules as four sentences, because under pressure two of them will swap. Learn the curve and derive them, then check each derivation against the inequality as the subject writes it, paying particular attention to the sign on the loss case. For the mental-accounting material, practise stating fungibility and then naming one consequence of its failure, since that pairing is what policy questions want.
For the realized and paper distinction, rehearse the reference-point sentence, because it is what reconciles two apparently conflicting sets of findings.
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