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Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jul 2026

Summary

Interviewed at Google, got a data interpolation problem. Not much to say, it was a single technical question and the content was pretty thin on details.

Questions Asked (1)

Q1

Given a dataset with missing values, how would you interpolate the data to fill in the gaps?

Algorithms & Data StructuresData Modeling
AI HintsAI Generated

Suggested Approach

Start by clarifying the dataset characteristics (e.g., time series, spatial, or tabular) and the nature of missingness (MCAR, MAR, MNAR). Then discuss interpolation methods ranging from simple (linear, polynomial) to advanced (splines, kriging, ML-based), and justify your choice based on data properties and business goals.

Pro tip: Mention that interpolation is not always the best approach—sometimes imputation or model-based methods are more appropriate. Also, emphasize the importance of validating the filled data to avoid introducing bias.

1. Understand the Data and Missingness

Identify the data type (time series, spatial, etc.) and analyze the missingness pattern (random vs. systematic). This guides the choice of interpolation method.

2. Choose an Interpolation Method

Select a method based on data characteristics: linear for simple trends, spline for smooth curves, kriging for spatial data, or ML models for complex patterns.

3. Implement and Validate

Apply the interpolation, then validate using cross-validation or hold-out data to ensure the filled values are reasonable and do not introduce bias.

4. Consider Alternatives and Trade-offs

Discuss when interpolation might fail (e.g., large gaps, non-stationary data) and alternative approaches like multiple imputation or model-based prediction.

Key Points to Mention

  • Types of missing data: MCAR, MAR, MNAR and their implications
  • Interpolation methods: linear, polynomial, spline, kriging, and machine learning approaches
  • Trade-offs between simplicity and accuracy, and risk of overfitting
  • Validation techniques: cross-validation, visual inspection, and error metrics
  • Handling large gaps or non-stationary data
  • Ethical considerations: avoiding bias and ensuring data integrity

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