Machine Learning & AI Topics
Production machine learning systems, model development, deployment, and operationalization. Covers ML architecture, model training and serving infrastructure, ML platform design, responsible AI practices, and integration of ML capabilities into products. Excludes research-focused ML innovations and academic contributions (see Research & Academic Leadership for publication and research contributions). Emphasizes applied ML engineering at scale and operational considerations for ML systems in production.
Machine Learning Algorithms and Theory
Core supervised and unsupervised machine learning algorithms and the theoretical principles that guide their selection and use. Covers linear regression, logistic regression, decision trees, random forests, gradient boosting, support vector machines, k means clustering, hierarchical clustering, principal component analysis, and anomaly detection. Topics include model selection, bias variance trade off, regularization, overfitting and underfitting, ensemble methods and why they reduce variance, computational complexity and scaling considerations, interpretability versus predictive power, common hyperparameters and tuning strategies, and practical guidance on when each algorithm is appropriate given data size, feature types, noise, and explainability requirements.
Real Time Inference and Serving Constraints
Design and engineering considerations for serving models with strict latency and availability requirements. Topics include understanding latency budgets and service level objectives, choosing between batch and real time inference, synchronous versus asynchronous patterns, request batching, caching strategies, model warm start and cold start handling, graceful degradation and fallback policies, model optimization techniques such as quantization and pruning, trade offs between model complexity and inference cost, state and consistency management for online features, back pressure and queueing strategies, deployment orchestration, and operational monitoring and alerting for inference pipelines.
Model Selection and Hyperparameter Tuning
Covers the end to end process of choosing, training, evaluating, and optimizing machine learning models. Topics include selecting appropriate algorithm families for the task such as classification versus regression and linear versus non linear models, establishing training pipelines, and preparing data splits for training validation and testing. Explain model evaluation strategies including cross validation, stratification, and nested cross validation for unbiased hyperparameter selection, and use appropriate performance metrics. Describe hyperparameter types and their effects such as learning rate, batch size, regularization strength, tree depth, and kernel parameters. Compare and apply tuning methods including grid search, random search, Bayesian optimization, successive halving and bandit based approaches, and evolutionary or gradient based techniques. Discuss practical trade offs such as computational cost, search space design, overfitting versus underfitting, reproducibility, early stopping, and when to prefer simple heuristics or automated search. Include integration with model pipelines, logging and experiment tracking, and how to document and justify model selection and tuned hyperparameters.
Machine Learning in Lyft's Business Context
Application of machine learning engineering practices to Lyft's business problems, including demand forecasting, rider and driver matching, dynamic pricing, routing optimization, fraud detection, experimentation, ML productization, monitoring, and responsible AI within the ride-hailing domain.
Neural Networks and Optimization
Covers foundational and advanced concepts in deep learning and neural network training. Includes neural network architectures such as feedforward networks, convolutional networks, and recurrent networks, activation functions like rectified linear unit, sigmoid, and hyperbolic tangent, and common loss objectives. Emphasizes the mechanics of forward propagation and backward propagation for computing gradients, and a detailed understanding of optimization algorithms including stochastic gradient descent, momentum methods, adaptive methods such as Adam and RMSprop, and historical methods such as AdaGrad. Addresses practical training challenges and solutions including vanishing and exploding gradients, careful weight initialization, batch normalization, skip connections and residual architectures, learning rate schedules, regularization techniques, and hyperparameter tuning strategies. For senior roles, includes considerations for large scale and distributed training, convergence properties, computational efficiency, mixed precision training, memory constraints, and optimization strategies for models with very large parameter counts.
Machine Learning and Forecasting Algorithms
An in-depth coverage of machine learning methods used for forecasting and time-series prediction, including traditional time-series models (ARIMA, SARIMA, Holt-Winters), probabilistic forecasting techniques, and modern ML approaches (Prophet, LSTM/GRU, Transformer-based forecasters). Topics include feature engineering for seasonality and trend, handling non-stationarity and exogenous variables, model evaluation for time-series (rolling-origin cross-validation, backtesting, MAE/MAPE/RMSE), uncertainty quantification, and practical deployment considerations such as retraining, monitoring, and drift detection. Applies to forecasting problems in sales, demand planning, energy, finance, and other domains.
Neural Network Architectures: Recurrent & Sequence Models
Comprehensive understanding of RNNs, LSTMs, GRUs, and Transformer architectures for sequential data. Understand the motivation for each (vanishing gradient problem, LSTM gates), attention mechanisms, self-attention, and multi-head attention. Know applications in NLP, time series, and other domains. Discuss Transformers in detail—they've revolutionized NLP and are crucial for generative AI.
Model Evaluation and Validation Strategy
Designing principled validation and evaluation approaches to accurately estimate generalization and support model selection. Topics include cross validation strategies for different data types, holdout and temporal validation for time dependent data, metric selection aligned to product goals, nested validation to avoid selection bias, techniques to avoid label leakage, calibration and confidence estimation, sample size and statistical power considerations, multiple comparison correction, and practical pipelines to automate validation and track model performance over time.
Model Monitoring and Evaluation
Designing observability and evaluation practices to detect model degradation and to iterate responsibly in production. Topics include choosing health and quality metrics, drift detection and data distribution monitoring, alerting and diagnostic tooling, strategies for retraining and model rollback, offline to online evaluation gaps, and how to use A and B testing frameworks to validate improvements. Candidates should explain how to instrument models, interpret signals, and prioritize fixes in a production environment.