This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Optimize interval-scoring strategy states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
You are given a five-round interval-estimation game used in market-making interviews. In each round, the interviewer asks a quantitative question with an unknown true numeric answer A. You must report a closed interval [L, U]. Scoring per round: if A ∉ [L, U], score = 0; if A ∈ [L, U], score = L/U. The goal after five rounds is a total score ≥ 2.0. Assume for each round you can form a subjective probability distribution for A. a) Formulate the optimization to choose L and U that maximizes expected per-round score E[(L/U)·1{A∈[L,U]}] given a known continuous pdf for A. b) Derive first-order optimality conditions and discuss how the optimal coverage probability compares to conventional confidence levels under light- vs heavy-tailed beliefs. c) Describe a strategy to allocate risk across five rounds (e.g., dynamic programming or heuristic thresholds) to target total ≥ 2.0, including how to adjust interval tightness after early wins/losses. d) Provide a quick mental method for approximately optimal [L, U] under log-normal beliefs; explain how you’d adapt for heavy tails. e) Outline a simple simulation to validate your strategy and estimate its probability of meeting the ≥ 2.0 target.
Quick Answer: This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Optimize interval-scoring strategy states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
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Optimize interval-scoring strategy
Five-Round Interval-Estimation Game: Optimal Intervals and Risk Allocation
You play five independent rounds. In round i, an unknown numeric answer A is drawn from a continuous distribution. You announce a closed interval [L, U]. The round score is:
0 if A ∉ [L, U]
L/U if A ∈ [L, U]
Total score is the sum across five rounds. The target is total ≥ 2.0. Assume that for each round you have a subjective continuous pdf f(a) (cdf F) for A.
Answer the following:
(a) Formulate the optimization for choosing L and U that maximizes the expected per-round score E[(L/U)·1{A ∈ [L, U]}] given a known continuous pdf.
(b) Derive the first-order optimality conditions (FOCs). Discuss how the optimal coverage probability compares to conventional confidence levels under light- vs heavy-tailed beliefs.
(c) Describe a strategy to allocate risk across five rounds (e.g., dynamic programming or heuristics) to maximize the probability of achieving total ≥ 2.0, including how to adjust interval tightness after early wins/losses.
(d) Provide a quick mental method for approximately optimal [L, U] under log-normal beliefs (A > 0), and explain how you’d adapt for heavy tails.
(e) Outline a simple simulation to validate your strategy and estimate the probability of meeting the ≥ 2.0 target.
Assume U > 0 and typically A > 0 (most market-making questions are positive). If A could be negative, you may work on a transformed scale (e.g., log of absolute value) or restrict to positive-support questions.
Clarifying Questions to Ask Guidance
Clarify the random variables, distributional assumptions, independence assumptions, and desired output.
Show enough derivation for the interviewer to follow the reasoning.
Explain how you would validate the result with simulation or sensitivity checks.
What a Strong Answer Covers Guidance
A correct setup with definitions, formulas, and boundary conditions.
A step-by-step derivation or estimation plan.
Interpretation of the result, including uncertainty and practical limitations.
Checks for assumptions, edge cases, and numerical stability.
Follow-up Questions Guidance
How would the result change if the assumptions were relaxed?
Can you verify the answer with a simulation?
What is the most likely source of estimation error?