Designing Experimentation Guardrails

Introducing the Airbnb Experiment Guardrails framework, which helps us prevent negative impact on key metrics while experimenting at scale.

Tatiana Xifara
10 min readbeginner
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Overview

The article discusses the Experiment Guardrails framework implemented at Airbnb to mitigate negative impacts on key metrics during experimentation. It outlines the system's structure, including the three main guardrails designed to protect important metrics and ensure informed decision-making during product launches.

What You'll Learn

1

How to implement an Experiment Guardrails system to protect key metrics

2

Why selecting appropriate guardrail metrics is crucial for effective experimentation

3

When to escalate experiments based on guardrail triggers

Key Questions Answered

What is the purpose of the Experiment Guardrails system at Airbnb?
The Experiment Guardrails system at Airbnb is designed to prevent negative impacts on key metrics during product experimentation. It identifies potential negative effects before launch, ensuring that teams can make informed decisions and maintain overall company performance.
What are the three main guardrails in the Experiment Guardrails system?
The three main guardrails are the Impact Guardrail, which prevents large negative effects; the Power Guardrail, which ensures sufficient exposure for reliable results; and the Stat Sig Negative Guardrail, which escalates experiments showing statistically significant negative impacts.
How does Airbnb adjust the escalation thresholds for experiments?
Airbnb adjusts escalation thresholds based on global coverage, allowing for different thresholds depending on the percentage of visitors assigned to an experiment. This ensures that experiments with lower coverage have stricter thresholds to maintain the integrity of key metrics.
What happens to experiments that trigger guardrails?
Experiments that trigger guardrails must go through an escalation process where stakeholders discuss the results transparently. This process helps ensure that any potential negative impacts are thoroughly analyzed before proceeding with the launch.

Key Statistics & Figures

Percentage of experiments flagged for escalation
25 experiments per month
This indicates the volume of experiments that require additional review due to potential negative impacts.
Percentage of flagged experiments that launch after discussion
80%
This shows that most escalated experiments are deemed acceptable after stakeholder review.
Percentage of flagged experiments that are stopped before launch
20%
This highlights the effectiveness of the guardrails in preventing potentially harmful experiments from proceeding.

Key Actionable Insights

1
Implementing a guardrail system can significantly enhance your experimentation process by providing a structured approach to evaluating potential impacts on key metrics.
This system allows teams to make informed decisions and reduces the risk of negative outcomes, which is especially important in environments with multiple concurrent experiments.
2
Regularly review and adjust your guardrail metrics to align with evolving business priorities and ensure they remain relevant.
As company strategies change, the metrics that are deemed critical may also shift, necessitating updates to the guardrail system to maintain its effectiveness.
3
Utilize historical data to set appropriate thresholds for your guardrails, balancing the need for sensitivity with the operational feasibility of experimentation.
Analyzing past experiments can help you determine what thresholds are practical and effective, minimizing unnecessary escalations while still protecting key metrics.

Common Pitfalls

1
One common pitfall is overloading the guardrail system with too many metrics, which can lead to increased false positives and slower decision-making.
When too many metrics are monitored, the likelihood of false alerts rises, causing teams to waste time on unnecessary escalations and slowing down the experimentation process.
2
Failing to adjust escalation thresholds based on global coverage can lead to unfair evaluations of experiments with low participant numbers.
If all experiments are held to the same standard regardless of coverage, those with fewer participants may be unfairly penalized, leading to missed opportunities for valuable insights.