Handle missing values for LGD modeling

Quick Overview

Handle missing values for LGD modeling evaluates core ML concepts, assumptions, math intuition, training/evaluation trade-offs, and practical failure modes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

Handle missing values for LGD modeling

Company: Wells Fargo

Role: Data Scientist

Category: Machine Learning

Difficulty: medium

Interview Round: Technical Screen

How would you handle missing values in a dataset used for LGD modeling? Compare multiple imputation, model‑based imputation, business‑rule fills, indicator variables, and conditions where leaving missingness explicit is preferable.

Quick Answer: Handle missing values for LGD modeling evaluates core ML concepts, assumptions, math intuition, training/evaluation trade-offs, and practical failure modes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

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Wells Fargo
Jul 26, 2025
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Handle missing values for LGD modeling

Handling Missing Values for LGD Modeling

Context

You are building a Loss Given Default (LGD) model using account- and borrower-level features captured around the time of default. The dataset contains both continuous and categorical variables with non-trivial missingness due to reporting gaps, system migrations, and process differences across products/regions.

Task

Describe how you would handle missing values in this LGD modeling context. Specifically, compare the following approaches:

  1. Multiple imputation (e.g., MICE)
  2. Model-based imputation (e.g., kNN, random forest, regression)
  3. Business-rule fills (domain-driven heuristics)
  4. Indicator variables (missingness flags; Unknown category)
  5. Leaving missingness explicit (letting the model handle NA directly)

For each, explain:

  • Assumptions about the missingness mechanism (MCAR, MAR, MNAR)
  • Pros, cons, and typical use cases in LGD modeling
  • Guardrails to avoid bias and leakage
  • How you would validate the choice and measure impact on LGD performance and stability

Clarifying Questions to Ask Guidance

  • Clarify the task, data shape, labels, constraints, and evaluation metric.
  • State assumptions behind the math or modeling technique you choose.
  • Connect theory to practical training, debugging, and deployment implications.

What a Strong Answer Covers Guidance

  • Correct definitions and formulas where the prompt requires them.
  • A practical explanation of how the method behaves on real data.
  • Trade-offs, failure modes, diagnostics, and mitigation strategies.
  • Evaluation choices that match the product or modeling objective.

Follow-up Questions Guidance

  • How would noisy labels, class imbalance, or distribution shift affect the answer?
  • What would you monitor after deployment?
  • Which baseline would you compare against first?
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