Experiment Prioritization & Roadmap Questions
Running experimentation as a program: building and ranking a test backlog, prioritizing ideas by expected impact and effort, and sustaining experimentation velocity and iteration cadence. Covers scaling and rolling out winning variants, and the learning loop that feeds the next round of tests. The scope is the operating rhythm of a testing program, not the design of any single test.
MediumTechnical
25 practiced
Write a Python function benjamini_hochberg(p_values, q) that takes a list or numpy array of p-values and returns a boolean array indicating which null hypotheses are rejected under Benjamini-Hochberg FDR control at level q. Handle unordered p-values and return results aligned with the original input order.
MediumTechnical
30 practiced
Implement an online experiment evaluator in Python that consumes a stream of aggregates for control and treatment (control_events, control_trials, treat_events, treat_trials) returned per time window. The evaluator should perform a two-sample z-test at each window but apply a Pocock alpha-spending correction to control type I error when 'peeking'. API: evaluate_stream(stream_iter, alpha=0.05, min_samples=100, max_windows=1000) -> {decision, p_value, window_index}. Describe assumptions and edge cases.
HardSystem Design
28 practiced
Describe architecture and engineering required to support real-time model comparisons: shadow deployments, online A/B between model versions, minimal data skew, time synchronization across services, replay capability for deterministic comparison, and handling non-deterministic model outputs. Cover telemetry, storage, and evaluation strategies to ensure fair comparisons.
MediumSystem Design
29 practiced
Your existing experiment platform only supports fixed A/B tests. Describe how you would add support for multi-armed bandits: changes to data collection and logging, an online policy engine, requirements for offline evaluation and logging propensities, UI changes for experiment owners, and guardrails to prevent runaway allocations. Also explain how to support both an exploratory phase and an exploitative phase.
HardTechnical
32 practiced
Deep dive: Explain alpha-spending methods for sequential testing (Pocock and O'Brien-Fleming). Provide intuition for how spending functions control overall type I error across multiple interim looks, describe the typical spending patterns and pros/cons of each approach, and give practical recommendations for ML product experiments where teams frequently peek at dashboards.
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