This is where most of the conversation lived.
Start by clarifying the business objective and defining the target variable precisely, then outline the ML formulation (regression vs. classification) and discuss feature engineering across temporal, spatial, order, and external data. Emphasize trade-offs like data leakage, real-time vs. batch features, and evaluation metrics aligned with business impact.
Pro tip: Frame the problem in terms of Grab's operational constraints: predicting fulfillment time for real-time dispatch requires low-latency features and careful handling of censored data (e.g., orders not yet delivered). Mention how you'd validate with time-based splits and monitor for concept drift.
Define what 'order fulfillment time' means (e.g., from order placement to delivery) and whether to predict it as a continuous value (regression) or as a category (e.g., on-time vs. late). Consider if the prediction is needed pre-dispatch or post-dispatch.
Choose the ML task: regression for exact time, quantile regression for uncertainty, or classification for SLA breach. Discuss loss functions (e.g., MAE, pinball loss) and evaluation metrics (e.g., RMSE, MAPE, or business KPIs like % on-time).
Brainstorm features across categories: temporal (hour, day, peak), spatial (distance, traffic), order (size, cuisine), driver (experience, load), and external (weather, events). Highlight real-time vs. historical features and avoid leakage.
Discuss handling missing data, censored data (orders not yet completed), and imbalanced data if classifying. Mention techniques like survival analysis or using only completed orders with careful bias correction.
Propose time-based validation (e.g., rolling window) to mimic production. Discuss deployment considerations: feature store, latency, model retraining frequency, and monitoring for drift.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Went with gradient boosted trees, cited interpretability and performance on tabular data with mixed feature types.
Start by clarifying the problem context, including data size, feature types, and business objective, then propose a baseline model and a more complex alternative, justifying your choice based on trade-offs. Finally, outline a robust evaluation strategy that includes appropriate metrics, validation techniques, and consideration of business impact.
Pro tip: Demonstrate awareness of Grab's operational constraints (e.g., real-time inference, scalability) by discussing how model choice affects latency and cost, not just accuracy.
Ask about data size, feature types, linearity, and business goal to understand the regression task's specifics.
Suggest a baseline (e.g., linear regression) and a more complex model (e.g., gradient boosting), explaining their strengths and weaknesses.
Select a model based on trade-offs like interpretability, performance, training time, and inference latency, aligning with business needs.
Describe metrics (e.g., RMSE, MAE), validation (e.g., time-series split), and how to monitor business KPIs.
Mention how the model will be deployed, retrained, and monitored for drift and performance degradation.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.