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Questions and Answers
What is the end-of-period wealth for investment 1 if the investor gains $10?
What is the end-of-period wealth for investment 1 if the investor gains $10?
The end-of-period wealth for investment 1 would be $2010.
What is the expected utility for investment 2 given its probabilities and outcomes?
What is the expected utility for investment 2 given its probabilities and outcomes?
The expected utility for investment 2 is approximately 7.601.
What is the Pratt-Arrow risk premium for investment 1?
What is the Pratt-Arrow risk premium for investment 1?
The Pratt-Arrow risk premium for investment 1 is $0.
Calculate the expected wealth for investment 2 considering the probabilities and outcomes.
Calculate the expected wealth for investment 2 considering the probabilities and outcomes.
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What key difference exists between the Pratt-Arrow risk premium and Markowitz's risk premium?
What key difference exists between the Pratt-Arrow risk premium and Markowitz's risk premium?
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What is the variance of end-of-period wealth used for in investor choice theory?
What is the variance of end-of-period wealth used for in investor choice theory?
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What does the term 'stochastic dominance' refer to in investor choice theory?
What does the term 'stochastic dominance' refer to in investor choice theory?
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How does the normality assumption simplify decision-making for investors?
How does the normality assumption simplify decision-making for investors?
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What is the formula for the Pratt-Arrow measure of a local risk premium?
What is the formula for the Pratt-Arrow measure of a local risk premium?
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Define Absolute Risk Aversion (ARA).
Define Absolute Risk Aversion (ARA).
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What does Relative Risk Aversion (RRA) measure?
What does Relative Risk Aversion (RRA) measure?
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For a power utility function $U(W) = -W^{-α}$, what can be inferred about ARA and RRA?
For a power utility function $U(W) = -W^{-α}$, what can be inferred about ARA and RRA?
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Given the logarithmic utility function $U(W) = \ln(W)$, how do ARA and RRA behave?
Given the logarithmic utility function $U(W) = \ln(W)$, how do ARA and RRA behave?
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What does the expected utility formula represent in terms of wealth?
What does the expected utility formula represent in terms of wealth?
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How do utility functions differ among individuals?
How do utility functions differ among individuals?
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Explain how uncertainty impacts rational decision-making in investment.
Explain how uncertainty impacts rational decision-making in investment.
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What is the relationship between the local risk premium and investor choice?
What is the relationship between the local risk premium and investor choice?
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Define a risk-averse investor.
Define a risk-averse investor.
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What role does the uncertainty of returns play in the investor's judgment?
What role does the uncertainty of returns play in the investor's judgment?
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What is characteristic of a risk-neutral investor's decision-making process?
What is characteristic of a risk-neutral investor's decision-making process?
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What motivates a risk lover in investing?
What motivates a risk lover in investing?
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How can we express the expected utility of end-of-period wealth mathematically?
How can we express the expected utility of end-of-period wealth mathematically?
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In the context of a fair gamble, what factors influence an investor's decision to invest or not?
In the context of a fair gamble, what factors influence an investor's decision to invest or not?
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What is the role of risk attitude in rational decision making under uncertainty?
What is the role of risk attitude in rational decision making under uncertainty?
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How does a risk-averse investor typically respond to uncertain outcomes?
How does a risk-averse investor typically respond to uncertain outcomes?
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What is meant by 'certainty equivalent wealth' in investment choices?
What is meant by 'certainty equivalent wealth' in investment choices?
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What characterizes a risk-loving investor's utility function?
What characterizes a risk-loving investor's utility function?
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How does the expected utility differ for a risk-neutral investor?
How does the expected utility differ for a risk-neutral investor?
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What does the risk premium represent in investment decisions?
What does the risk premium represent in investment decisions?
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In the provided investment scenario, what does it mean when expected end-of-period wealth is equal for both alternatives?
In the provided investment scenario, what does it mean when expected end-of-period wealth is equal for both alternatives?
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What is the relationship between expected wealth and utility for risk-averse investors?
What is the relationship between expected wealth and utility for risk-averse investors?
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Describe how attitudes towards risk can influence investment choices.
Describe how attitudes towards risk can influence investment choices.
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In the context of normally distributed random variables, what two parameters fully describe a normal distribution?
In the context of normally distributed random variables, what two parameters fully describe a normal distribution?
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How is the expected return $R̄$ defined in terms of asset returns?
How is the expected return $R̄$ defined in terms of asset returns?
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What is the relationship between end-of-period wealth and returns under the normality assumption?
What is the relationship between end-of-period wealth and returns under the normality assumption?
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What does the variance of returns, $ heta_R^2$, represent?
What does the variance of returns, $ heta_R^2$, represent?
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What does it mean when we say returns are normally distributed, denoted as $R ∼ N(R̄, heta_R^2)$?
What does it mean when we say returns are normally distributed, denoted as $R ∼ N(R̄, heta_R^2)$?
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Explain the implication of rational decision-making based solely on mean and variance in investment contexts.
Explain the implication of rational decision-making based solely on mean and variance in investment contexts.
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What formula represents the calculation for the variance of returns using end-of-period wealth?
What formula represents the calculation for the variance of returns using end-of-period wealth?
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In the equation for expected return, what does $W_0$ represent?
In the equation for expected return, what does $W_0$ represent?
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What significance does the mean, $ar{W}$, hold in investment decision-making?
What significance does the mean, $ar{W}$, hold in investment decision-making?
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How do you express the variance of wealth, $ heta_W^2$, in terms of expected wealth?
How do you express the variance of wealth, $ heta_W^2$, in terms of expected wealth?
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What are the two key definitions of risk aversion introduced by Pratt and Arrow?
What are the two key definitions of risk aversion introduced by Pratt and Arrow?
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If an investor's utility function is defined as U(W) = W^2, how would they generally respond to a risky investment?
If an investor's utility function is defined as U(W) = W^2, how would they generally respond to a risky investment?
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What does the expected utility theory suggest about the relationship between risk and utility?
What does the expected utility theory suggest about the relationship between risk and utility?
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How is the certainty equivalent (CE) calculated in the context of risky investments?
How is the certainty equivalent (CE) calculated in the context of risky investments?
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Explain the significance of the risk premium in relation to end-of-period wealth.
Explain the significance of the risk premium in relation to end-of-period wealth.
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What are the implications of an actuarially neutral gamble on the expected wealth of an investor?
What are the implications of an actuarially neutral gamble on the expected wealth of an investor?
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In the context of risk aversion, what does a utility function of U(W) = ln(W) indicate?
In the context of risk aversion, what does a utility function of U(W) = ln(W) indicate?
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Describe how Taylor series expansion is used in the context of investment utility functions.
Describe how Taylor series expansion is used in the context of investment utility functions.
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What is the expected value of a gamble with outcomes z1 and z2 with probabilities p1 = p2 = 0.5 when E(z1 + z2) = 0?
What is the expected value of a gamble with outcomes z1 and z2 with probabilities p1 = p2 = 0.5 when E(z1 + z2) = 0?
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How does the level of risk aversion affect investment decisions?
How does the level of risk aversion affect investment decisions?
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Study Notes
Principles of Finance - Lecture 5: Utility Theory Under Uncertainty
- Utility theory under uncertainty is a rational decision-making framework for situations with unknown future outcomes.
- Previously, decisions were made under certainty, where market interest rates and investment returns were known.
- Uncertainty now exists because future market interest rates and subsequent returns are unknown.
- Today's lecture focuses on the theory of rational decision-making under uncertainty, guiding investor choices among risky alternatives.
- Key considerations include risk aversion, time preferences, and choice objects.
- This framework is used to analyze how investors approach and choose actions in uncertain environments.
Axioms of Choice Under Uncertainty
- Axiom 1: Comparability (completeness): An investor can compare any two investment options. Either one is preferred, the other is preferred, or they are equivalent.
- Axiom 2: Transitivity: If an investor prefers option X to Y, and Y to Z, then they must prefer X to Z.
- Axiom 3: Strong Independence: An investor's preferences remain consistent when presented with probabilistic outcomes.
- Axiom 4: Measurability: Utility of outcomes/choices can be numerically quantified.
- Axiom 5: Ranking: Investment preferences can be ranked consistently. If all axioms hold, choices are rational and coherent.
Utility Functions
- Utility functions represent an investor's preferences for risky outcomes.
- Utility functions are order-preserving, meaning if one outcome is preferred to another, its corresponding utility value is also greater.
- Utility functions uniquely rank outcomes and can be used to evaluate combinations (expected utility).
- Expected utility is calculated by weighing the utility of each possible outcome by its probability.
Expected Utility
- Maximizing expected utility from end-of-period wealth is the goal of a rational investor under uncertainty.
- The formula for expected utility is
- E[U(W)] = ΣpᵢU(Wᵢ)
- where:
- S is the set of uncertain alternatives,
- i is a specific alternative,
- pᵢ is the probability of alternative i,
- Wᵢ is the wealth for alternative i.
Risk Profiles of Investors
- Risk Averse: Investors dislike risk and need compensation for taking it.
- Risk Neutral: Investors are indifferent to risk, considering only expected wealth.
- Risk Lover: Investors prefer risk and need compensation for avoiding it.
Certainty Equivalent Wealth and Risk Premium
- Certainty equivalent wealth (CE): The level of wealth an investor would accept with certainty.
- Risk premium (π): The difference between the expected value and the certainty equivalent.
- π = E(W) - CE
- This reflects an investor's aversion to uncertainty.
Risk Profile of the Investor
- Three types of risk profiles exist: risk averse, risk neutral, risk lover, all reflected in an investor's utility function.
Level of Risk Aversion
- Absolute risk aversion (ARA) and relative risk aversion (RRA), key indicators of investor risk sensitivity.
- Investors are commonly risk-averse.
- ARA and RRA are calculated using derivatives of a utility function
- ARA= U''(W)/U'(W)
- RRA= -W(U''(W)/U'(W))
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Description
Explore the Utility Theory under uncertainty in this insightful lecture. Understand how rational decision-making applies when future outcomes are unknown, focusing on risk aversion and investor choices. Key axioms guide how choices are made in uncertain environments.