Design an A/B Testing Platform
Problem Statement
Design an internal A/B testing platform for a large consumer product.
Core Functionality
The platform must enable product managers and engineers to:
- Create and manage experiments.
- Define experiment variants.
- Specify targeting rules for user segments.
- Set and adjust rollout percentages for variants.
- Safely start, stop, and ramp experiments.
User Assignment
For every incoming user request, the system must:
- Deterministically assign the user to a specific variant.
- Ensure this variant assignment remains sticky across multiple user sessions.
Data Collection & Analysis
The platform is responsible for:
- Logging user exposures to specific variants.
- Collecting downstream events related to user interactions.
- Enabling teams to compute critical business metrics such as click-through rate (CTR), conversion, retention, and revenue based on collected data.
Discussion Areas
Candidates should be prepared to discuss the following aspects of their design:
- Core requirements and API design.
- Experiment configuration management and versioning strategies.
- Traffic allocation mechanisms, including bucketing and ensuring mutual exclusion between experiments.
- Exposure logging and robust event ingestion pipelines.
- Metric computation, aggregation, and reporting.
- Operational aspects like real-time monitoring, safe ramp-up, rollback procedures, and guardrails.
- Statistical correctness considerations, such as detecting sample ratio mismatch (SRM), filtering bot traffic, and preventing double counting of events.
- Trade-offs related to scalability, reliability, and data freshness.
AI interview prep
Core dilemma
Balancing low-latency, highly consistent, and deterministic user assignment at massive scale with robust, statistically sound, and high-volume event ingestion and metric computation.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Design an A/B Testing Platform
Problem Statement
Design an internal A/B testing platform for a large consumer product.
Core Functionality
The platform must enable product managers and engineers to:
- Create and manage experiments.
- Define experiment variants.
- Specify targeting rules for user segments.
- Set and adjust rollout percentages for variants.
- Safely start, stop, and ramp experiments.
User Assignment
For every incoming user request, the system must:
- Deterministically assign the user to a specific variant.
- Ensure this variant assignment remains sticky across multiple user sessions.
Data Collection & Analysis
The platform is responsible for:
- Logging user exposures to specific variants.
- Collecting downstream events related to user interactions.
- Enabling teams to compute critical business metrics such as click-through rate (CTR), conversion, retention, and revenue based on collected data.
Discussion Areas
Candidates should be prepared to discuss the following aspects of their design:
- Core requirements and API design.
- Experiment configuration management and versioning strategies.
- Traffic allocation mechanisms, including bucketing and ensuring mutual exclusion between experiments.
- Exposure logging and robust event ingestion pipelines.
- Metric computation, aggregation, and reporting.
- Operational aspects like real-time monitoring, safe ramp-up, rollback procedures, and guardrails.
- Statistical correctness considerations, such as detecting sample ratio mismatch (SRM), filtering bot traffic, and preventing double counting of events.
- Trade-offs related to scalability, reliability, and data freshness.