Expected Value and Random Variables

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Questions and Answers

When a variable can take on different values, it is a:

  • Random variable (correct)
  • Dependent variable
  • Exogenous variable
  • Independent variable

The expected value is:

  • The product of the sums of the probability and the values in different states
  • The sum of the products of the probability and the values in different states (correct)
  • The difference between the products of the probability and the values in different states
  • The difference between the sums of the probability and the values in different states

Heads and tails are equally likely, but you win a dollar on heads and lose a dollar on tails. The expected value is:

  • $0.50
  • $1.00
  • $0.00 (correct)
  • -$0.50

Heads and tails are equally likely, but you win $2.00 on heads and lose $1.00 on tails. The expected value is:

<p>$0.50 (D)</p> Signup and view all the answers

Heads and tails are equally likely, but you win $3.00 on heads and lose $1.00 on tails. The expected value is:

<p>$1.00 (A)</p> Signup and view all the answers

You can invest $100,000 into either project A or B. You estimate that A succeeds with probability 0.7, doubling in value if it succeeds. Project B succeeds with probability 0.6. You should invest in:

<p>Project A (A)</p> Signup and view all the answers

You can invest $100,000 into either project A or B. You estimate that A succeeds with probability 0.6, while project B succeeds with probability 0.7. You should invest in:

<p>Project A (D)</p> Signup and view all the answers

You can invest $100,000 into either project A or B. You estimate that A succeeds with probability 0.5 while project B succeeds with probability 0.8. You should invest in:

<p>Cannot tell from the information presented (C)</p> Signup and view all the answers

You can invest in either project A or B. Project A has value $100 with probability 0.1 and value $75 with probability 0.9. Project B has value $110 with probability 0.2 and value $70 with probability 0.8. You should invest in:

<p>Cannot tell from the information presented (D)</p> Signup and view all the answers

Three possibilities are equally likely with payoffs of $3, $6, and $9. The expected value is:

<p>$6 (A)</p> Signup and view all the answers

Four possibilities are equally likely with payoffs of $2, $4, $6, and $8. The expected value is:

<p>$5 (A)</p> Signup and view all the answers

Half of all potential customers would pay $10 for your product but half would pay $8. Your marginal costs are $4. If you set the price at $10, the expected profit is:

<p>$3 (A)</p> Signup and view all the answers

A movie executive must decide to fund a new movie project. A success would earn $20 million and a failure would cost $60 million in lost profits. At what probability of expected success should he fund the movie?

<p>0.75 (C)</p> Signup and view all the answers

A pharmaceutical company must decide whether to fund a new drug development project. A success would earn $10 million and a failure would cost $90 million. At what probability of expected success should she fund the project?

<p>0.10 (B)</p> Signup and view all the answers

Which types of poor decisions are more visible to a decision maker's supervisor?

<p>Agreeing to undertake a project (A)</p> Signup and view all the answers

The key distinction between risk and uncertainty is:

<p>Uncertainty refers to not knowing possible outcomes or their probabilities (D)</p> Signup and view all the answers

The expected value of a gamble that pays $10 with probability 0.2 and -$4 with probability 0.8 is:

<p>$-1.20 (B)</p> Signup and view all the answers

You want to run a difference-in-difference experiment with a price increase for your lawn chairs in Miami. If you are worried about the 'representativeness' of your control group, a good comparison city would be:

<p>Tampa Bay (D)</p> Signup and view all the answers

You want to run a difference-in-difference experiment with a price increase for the bacon cheeseburger item on your menu. If you are worried about 'leakage' with your control group, a good comparison menu item would be:

<p>Soft drink sales (D)</p> Signup and view all the answers

A false positive is:

<p>When you incorrectly conclude that your hypothesis is true (A)</p> Signup and view all the answers

A false negative is:

<p>When you incorrectly conclude that your hypothesis is false (A)</p> Signup and view all the answers

We worry that false negatives occur too often relative to false positives due to:

<p>Managers having an incentive to make a false negative conclusion because they are harder for superiors to observe (B)</p> Signup and view all the answers

What are the Type I and Type II error costs?

<p>$490,000 and $150,000</p> Signup and view all the answers

Based on expected error costs, you should fund a project if it has better than what percentage chance of success?

<p>60% (D)</p> Signup and view all the answers

What should you do if the average probability from studies is less than your threshold for funding?

<p>You should not open the store.</p> Signup and view all the answers

When devising a strategy with considerable uncertainty, what is the recommended approach?

<p>Leave room for improvisation. (C)</p> Signup and view all the answers

What is the expected value of an uncertain outcome calculated as?

<p>The sum of probabilities times the random variables (A)</p> Signup and view all the answers

What should you consider if your uncle offers you a deal with an expected value much greater than the cost?

<p>All of the above. (D)</p> Signup and view all the answers

If you calculate the expected value of option A is greater than option B by 0.013%, what is your likely course of action?

<p>Flip a coin (B)</p> Signup and view all the answers

When deciding whether to sell widgets for $5 or $6, which price yields higher profits?

<p>Both prices earn the same profits (D)</p> Signup and view all the answers

You might increase your profits by:

<p>Setting a $6 price but offering a $1 discount (C)</p> Signup and view all the answers

Selection bias occurs because:

<p>There are systematic differences between treatment and control groups (C)</p> Signup and view all the answers

Why are randomized experiments considered the 'gold standard'?

<p>Selection bias is eliminated (C)</p> Signup and view all the answers

What is the key determinant of a careful observational study?

<p>The control group mimics the treatment group (A)</p> Signup and view all the answers

If you reject a correct hypothesis, what error are you committing?

<p>Type I error (D)</p> Signup and view all the answers

A manager will decide to fund too few projects if:

<p>All of the above. (D)</p> Signup and view all the answers

What is the difference between risk and uncertainty?

<p>None of the above. (D)</p> Signup and view all the answers

How can you deal with uncertainty effectively?

<p>Add flexibility to allow responses (C)</p> Signup and view all the answers

What is the expected value of guessing on a multiple-choice test with five options?

<p>0 points</p> Signup and view all the answers

What is the expected value of NPV when considering a new store with different probabilities?

<p>$4.0 million (A)</p> Signup and view all the answers

What is the expected profit or loss from adding a new manufacturing line with varying probabilities?

<p>Gain of $47,000</p> Signup and view all the answers

What is the expected NPV of a viral mobile app investment?

<p>$0 (A)</p> Signup and view all the answers

What is the minimum probability of success required to invest in a project with an NPV of $75 million?

<p>1/4 (D)</p> Signup and view all the answers

What do you estimate the referrals per dollar are through agency A?

<p>1.1 referrals per dollar (C)</p> Signup and view all the answers

What is the probability that a random customer will use the coupon if 90 out of 3,000 responded?

<p>0.03 (B)</p> Signup and view all the answers

What are the expected error costs of shutting down process B first?

<p>$16,000 (D)</p> Signup and view all the answers

What price maximizes expected revenue if 40% value it at $10 and 60% at $6?

<p>$6 (B)</p> Signup and view all the answers

You should enter the market if you believe the probability that the incumbent will price low is less than what percentage?

<p>0.75 (D)</p> Signup and view all the answers

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Study Notes

Random Variables and Expected Value

  • A random variable can take on different values.
  • The expected value is calculated as the sum of the products of probabilities and outcomes.

Expected Value in Gamble Scenarios

  • If winning $1 on heads and losing $1 on tails, expected value is $0.
  • Winning $2 on heads and losing $1 on tails results in an expected value of $0.50.
  • Winning $3 on heads and losing $1 on tails leads to an expected value of $1.00.

Investment Decisions

  • Comparing projects A and B indicates investing in project A is favorable when A's expected success probability is 0.7.
  • If project A has a 0.5 probability of success, it's indeterminate if A or B should be chosen.

Calculating Expected Values

  • For three equally likely outcomes with payoffs of $3, $6, and $9, the expected value is $6.
  • The expected value of four payoffs of $2, $4, $6, and $8 is $5.

Profit Calculations

  • If high-value customers pay $200 and low-value customers pay $175, expected profit per customer is $75 when marginal costs are $100.

Experiment Methodologies

  • Difference-in-difference estimates compare changes in outcomes between treatment and control groups to assess effects like price changes or advertising increases.

Cost-Benefit Analyses

  • For decisions such as funding projects with expected success, funding is justified when the probability exceeds specific thresholds (e.g., 0.75 for a movie project).

Error Types in Hypotheses

  • A "false positive" occurs when a hypothesis is incorrectly accepted.
  • Conversely, a "false negative" is the incorrect rejection of a hypothesis.

Risk and Uncertainty

  • Risk is quantifiable, while uncertainty involves unknown potential outcomes and their probabilities.

Managerial Decisions

  • An inclination to avoid false positives often influences managerial decision-making patterns.
  • Decisions made by managers may be influenced by the perceived visibility of outcomes, with major decisions likely scrutinized more heavily.

Strategies for Uncertainty

  • In uncertain situations, develop flexible strategies that allow for improvisation rather than rigid plans that fail to adapt to unforeseen events.

Calculation Framework

  • The expected value is derived from summing the product of probabilities and their associated values to inform decision-making.### Project Valuation Considerations
  • Valuation may underestimate project value in worst-case scenarios.
  • Success likelihood of the deal may be overvalued.

Decision-Making in Expected Values

  • If the expected value of option A is only slightly higher than option B, it’s reasonable to flip a coin instead of choosing definitively.

Pricing Strategies for Widgets

  • Selling at $5 and $6 with a marginal cost of $3 leads to equal profits due to different success rates.
  • Higher profits may be achieved by strategically pricing at $6 with a discount when negotiations stall.

Understanding Selection Bias

  • Selection bias arises from systematic differences between treatment and control groups impacting outcomes.

Importance of Randomized Controlled Experiments

  • These experiments eliminate selection bias, ensuring no systematic differences affect treatment and control groups.

Observational Study Quality

  • A strong observational study must ensure the control group mirrors the treatment group without systematic differences.

Hypothesis Testing Errors

  • Rejecting a true hypothesis results in a Type I error, indicating a false positive.

Project Funding Decisions

  • Managers may underfund uncertain projects due to known failures, lack of exposure to passed opportunities, and inadequate review processes.

Risk vs. Uncertainty

  • Neither risk nor uncertainty is accurately explained by typical definitions; they are distinct concepts in decision analysis.

Flexibility in Uncertain Situations

  • Strategies should incorporate flexibility to adapt to unforeseen contingencies.

Expected Value in Random Guessing

  • Random guessing on a multiple-choice test results in an expected value of zero, considering correct and incorrect answers.

Valuation of New Store Opportunities

  • The expected NPV for a new store considering varying population growth scenarios is estimated at $4 million.

Expected Profit/Loss Calculation

  • A new manufacturing line could yield an expected gain of $47,000 based on calculated probabilities.

NPV of a New Mobile App Investment

  • Expected NPV for a mobile app, factoring in probability of success and failure scenarios, results in an NPV of zero.

Investment Decision Threshold

  • For a project with potential NPVs of $75 million and -$25 million, a minimum success probability of 25% is necessary for investment justification.

Referral Effectiveness in Advertising

  • Agency A provides an estimated 1.1 referrals per dollar spent, based on increased ad spend and changes in referrals.

Probability of Coupon Usage

  • In a customer list of 3,000, the probability of coupon usage is 3%, based on past response rates.

Error Costs in Process Investigation

  • Investigating process A first has expected error costs of $16,000 versus lower costs for process B.

Pricing for Maximum Revenue

  • The optimal price to maximize expected revenue is $6, catering to varying buyer valuations.

Market Entry Considerations

  • Entering a market is justifiable if there is a belief that the incumbent’s likelihood of pricing low is below 75%.

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