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Upstart·Data Scientist·Onsite - Multi Round·Intermediate

Intermediate
Apr 2026

Summary

Onsite ML case at Upstart for a Data Scientist role. The session was focused on a single meaty problem about missing training data and how you'd still ship a model that generalizes. Not a lot of back-and-forth, more like a design session where they watched you think out loud.

Questions Asked (1)

Q1

You're working with California housing data but the training set is missing the lowest income bracket (under $25k). How do you build a model that still generalizes well to that unseen group?

Technical Trade-offsAdaptability & AmbiguityData Modeling
Author's notes

This one took me a second to even parse correctly.

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AI HintsAI Generated

Suggested Approach

Acknowledge the missing data issue and propose a multi-faceted strategy that includes data augmentation, robust modeling techniques, and careful evaluation. Emphasize the importance of understanding the potential impact on model fairness and generalization, and suggest ways to mitigate bias.

Pro tip: Consider using domain adaptation or transfer learning from a related dataset that includes the missing income bracket, and always validate with a holdout set that simulates the missing group to test generalization.

1. Assess the Impact

Analyze how the missing income bracket affects the target variable distribution and feature relationships. Determine if the missingness is random or systematic.

2. Data Augmentation

Explore external data sources or synthetic data generation to approximate the missing group. Consider using techniques like SMOTE or generative models to create representative samples.

3. Model Selection and Regularization

Choose models that are robust to missing data and can generalize well, such as tree-based models or regularized linear models. Use techniques like importance weighting to account for the missing group.

4. Evaluation and Validation

Design a validation strategy that includes a holdout set simulating the missing group. Use metrics that assess fairness and generalization, such as subgroup performance and calibration.

5. Iterate and Monitor

Continuously monitor model performance on the underrepresented group and update the model as new data becomes available. Implement feedback loops to detect and mitigate bias.

Key Points to Mention

  • Importance of understanding the missing data mechanism (MCAR, MAR, MNAR)
  • Techniques for data augmentation and synthetic data generation
  • Model robustness and regularization methods
  • Evaluation metrics for fairness and generalization
  • Domain adaptation and transfer learning
  • Ethical considerations and potential bias in the model

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.