How Long Should You Run an Experiment in GemX

Experiment duration is one of the most common questions merchants ask when running A/B tests. Running an experiment too short or too long can lead to misleading results and poor decisions in GemX.

This guide explains how long to run an experiment and when it is safe to stop.

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What Is Experiment Duration

Experiment duration is the amount of time an experiment runs to collect enough data for reliable results.

In GemX, you control when an experiment starts and stops. The goal is to run it long enough for results to stabilize, not to end it as soon as one variant appears to win.

How Long Should You Run an A/B Test?

There is no single “correct” duration for all experiments.

An experiment should run long enough to collect stable data, not just enough to show an early winner. The right duration depends on traffic volume, conversion activity, and the type of change you are testing.

Use the ranges below as a starting point:

Important note: These are guidelines, not hard rules. Low-traffic stores may need longer experiments.

Run Long Enough to Cover Real Traffic Patterns

Experiment duration should reflect real customer behavior, not short-term fluctuations.

A valid experiment usually includes:

• Both weekdays and weekends

• Normal traffic variation

• At least one full buying cycle

Stopping before these patterns appear increases the risk of misleading results.

Traffic Volume Matters More Than Days

Duration is not just about time. It is about how much data you collect.

• High-traffic stores may reach stable results faster

• Low-traffic stores usually need longer experiments

• Fewer conversions cause more volatility early on

If your store receives limited traffic, extending the experiment is often safer than stopping early.

Notes by Experiment Type

• UI and copy tests: These tests often stabilize faster. If traffic is low, extend the duration to reduce noise.

• Layout and structure tests: Layout changes affect how users scan and interact with a page. Expect higher variability early on.

• Funnel and multipage experiments: These require more time because users may convert across multiple sessions.

• Pricing and offer experiments: These are high-impact tests. Short durations are risky and often misleading.

Important note: Always prioritize data stability over a fixed number of days. If results are still fluctuating, extend the experiment.

When You Should (and Should NOT) Stop an Experiment

When You Should NOT Stop an Experiment

Do not stop an experiment if:

• It has only been running for a few days

• One variant shows an early spike but results are unstable

• The test has not covered both weekdays and weekends

• Conversion rates fluctuate heavily day to day

• The experiment is running during a short-term campaign or sale

Early results are often noisy and unreliable.

When It’s Safe to Stop an Experiment

You can consider stopping an experiment when:

• Results remain consistent over multiple days

• Performance differences no longer swing significantly

• Traffic patterns look normal and stable

• The experiment has run long enough for your traffic level

• The outcome aligns with expected user behavior

At this stage, results are more likely to reflect real customer behavior.

Final Check Before Stopping

Before ending an experiment, ask one question:

If I rerun this experiment next week, would I expect the same result?

If the answer is yes, it is usually safe to stop and act on the outcome.

Learn more: How to Apply the Winning Variation and End Your Test Safely

Best Practices for Experiment Duration

• Define a minimum duration before launching an experiment

• Let results stabilize before making decisions

• Avoid checking results too frequently

• Match duration to experiment depth

• Avoid major store changes during an active experiment

• Extend the experiment if results remain unclear

• Focus on learning, not speed

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FAQs about Experiment Duration

How long should I run an A/B test in GemX?

Most experiments should run from 7 to 30 days, depending on traffic volume and experiment type. The key is to continue the test until results are stable, not to stop early when one variant temporarily looks better.

Can I stop an experiment early if one variant is winning?

It is not recommended. Early performance differences are often caused by data noise and may reverse as more data is collected over time.

What is the minimum duration for an experiment?

There is no fixed minimum duration, but most experiments should span at least one full business cycle, including both weekdays and weekends, to reduce bias.

Should low-traffic stores run experiments longer?

Yes. Stores with lower traffic typically need longer experiment durations to collect enough data and reach reliable conclusions.

Does GemX automatically decide experiment duration?

No. GemX gives you full control over when to start and stop experiments. You decide the duration based on data stability, traffic volume, and your optimization goals.

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