Lecture 8

Heuristics/Biases and Implications

[Part One – Application of Heuristics and Biases]

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Perception and Processing Constraints

Hold two conflicting ideas at the same time

Perception and the Frame

Perception is not just seeing what’s there – but it is influenced by the frame:

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Uncertainty effects human behaviour

Memory Tricks

Memory is not a simple matter of information retrieval:

Memory is emotional - mark memories

Heuristics

In many cases, delay is not feasible. Decisions need to be made, even if the environment is one of limited attention, information, and processing capacity, so shortcuts, or heuristics, are necessary.

Brain 'rule of thumb'

Type 1 & 2 Heuristics

Heuristics come in all shapes and sizes. One dichotomy is between those heuristics that are reflexive, autonomic, and noncognitive, and economise on effort (Type 1); and others, which are cognitive in nature (Type 2).

Example: Self-Preservation Heuristics

Hear a noise with an unknown source?

Food tasting off?

These make good sense and are autonomic. Other heuristics, which are more cognitive, are related to comfort with the familiar.

Example: Diversification Heuristic

The diversification heuristic suggests that people like to try a little bit of everything when choices are not mutually exclusive.



Example: Ambiguity Aversion

Example: Endowment Effect

Example: Information Overload

Representativeness

Conjunction fallacy: Venn diagram

Which seems more likely? A. Jane is a lottery winner. B. Jane is a happy lottery winner.

Many pick B, but A must have a higher probability, as a Venn diagram clearly shows.

Problem: conjunction fallacy.

An example of people having difficulty with probabilities is when they have no notion of the difference between simple probabilities (probability of A) and joint probabilities (probability of both A and B).

For example, they naturally feel that the probability that they will win the lottery and be overjoyed the next day is higher than the probability that they will just win the lottery.

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join probability, both of them happening at the same time

Base Rate Neglect and Bayes’ Rule

An important variant of representativeness is base rate neglect.

Bayes’ rule, a useful relationship that allows us to evaluate conditional probabilities:

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It says that the probability of event B, conditional on event A, is equal to the probability of event A, conditional on event B, times the ratio of the simple probabilities (base rates) of event B to event A.

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you would say 40% chance of rain.

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Base rate neglect would imply that you believe there is a _______________ chance of rain conditional on rain being predicted.

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Hot Hand Phenomenon

Gambler’s Fallacy

Gambler’s fallacy may apply if people are fairly sure about nature of population.

Overestimating Predictability

Recency:

Salience

Availability

Anchoring

People are initially anchored on their prior beliefs. Quickly multiply these eight numbers:

Most people will come up with a low estimate: anchored on the product of the first 4 or 5.

Example:

Anchoring vs. Representativeness

Which is right?

Conflicting result - anchoring vs representativeness

Some situations tend to anchor more, some tend to rely on new information

Anchoring vs. Representativeness ii.

Anchoring vs. representativeness iii.

[Part Two – Implications of Heuristics and Biases for Financial Decision-Making]

  1. Expectations influence perceptions:
  1. It has been argued that cognitive dissonance can:
  1. Diversification heuristic
  1. Ambiguity aversion
  1. Information overload
  1. Representativeness (and halo effects)
  1. Recency
  1. Anchoring and slow adjustment coupled with representativeness

While heuristics are usually excellent time- and effort saving decision-making mechanisms, they sometimes appear to lead investors in unfortunate directions. we return to these heuristics when we investigate their potential impact on the behavior of investors, future retirees, analysts, and managers, and how they may potentially impact market outcomes.

Home Bias

Domestic investors hold mostly domestic securities.

Investor international holdings

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Potential Home Bias Explanations

Why?

Excessive domestic optimism would imply a lot of disagreement among investor groups

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Home Bias Within a Country

Poor Diversification is Implied

Language

In Finland, there are two official languages, Finnish and Swedish.

Culture

Home Bias and Informational Advantage

A rational explanation for local preference is an informational advantage.

Evidence from Mutual Fund Manager Behaviour

Does Local Preference Boost Performance?

Can retail investors profit from local information?

Representativeness: “Good Companies are Good Investments”

But Do Executives Know Better?

  1. Quality of management
  2. Quality of products/services
  3. Innovativeness
  4. Long-term investment value
  5. Financial soundness
  6. Ability to attract, develop, and keep talented people
  7. Responsibility to the community and environment
  8. Wise use of corporate assets

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Small stock tend to perform better

Momentum-Chasing: Survey Evidence

  1. One with an “average return over the last 5 years of 5%”
  2. And a second with an “average return over the last 5 years of 15%.”

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Momentum-Chasing and Company Stock

In studying 401(k)s defined contribution plan members new allocations into company stock, Bernartzi (2001, JF) has established that much of it was from chasing winners. Forming portfolios based on 1-yr/10-yr own-company stock returns:

  1. Low-return portfolios had 21%/10% put into company stock
  2. High-return portfolios had 24%/40% put into company stock

Does chasing past returns make sense?

Academic evidence is somewhat subtle here:

Absolutely fine to go 50/50 and maximise diversification.

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Conclusion