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What is A/B testing?

A/B testing compares two variants (A control, B treatment) of a page, email, or ad for randomized audiences to see which performs better on a defined metric (conversion, click, revenue). Decisions need enough volume and statistical reading—not a gut call after 50 sessions.

In one sentence

A/B testing picks a winner with data, not opinions.

Key points

  • One clear hypothesis and one primary metric per test.
  • Randomization and enough duration to limit false positives.
  • Don’t peek and stop at the first swing.
  • At low traffic, prefer qualitative research or before/after tests.

Term at a glance

A/B testing
split testing · controlled experiment · bucket testing
English term
A/B testing
Domain
Digital marketing / UX
Category
Experimentation / CRO
Level
Intermediate

What does A/B testing mean?

It is experimental: isolate one change (headline, CTA, form) to estimate causal effect on conversion. Modern tools handle traffic splits.

Pitfalls: too many variants without traffic, ignoring seasonality, or calling winners on secondary metrics.

For Quebec SMEs with moderate traffic, tests on high-volume ad landings or email are more realistic than homepage tests at 200 sessions/week.

How do you run an A/B test?

  1. 01

    Write the hypothesis

    “Cutting the form from 8 to 4 fields increases leads by X%.”

  2. 02

    Pick metric and sample

    Primary conversion, minimum runtime, stop rules.

  3. 03

    Run the split

    Random 50/50, identical tracking, no other major changes.

  4. 04

    Decide and document

    Ship the winner; record learning even if inconclusive.

A concrete example

A Shopify store compares “Add to cart” vs “Reserve in Montreal store.” After 4 weeks and ~3,000 sessions each, B lifts appointments 18% without hurting average online order value.

What is A/B testing for?

Ad landings

Validate headlines and proof before scaling spend.

Email

Subjects and CTAs on large enough lists.

Checkout

Reduce cart abandonment.

Pricing pages

Test offer presentation, not only price.

Pros and cons

  • Evidence-based decisions
  • Fewer ego debates
  • Causal impact estimate
  • Reusable learnings
  • Needs volume
  • False-positive risk
  • Tooling cost
  • Does not replace user research

A/B testing vs expert review

A/B testingUX heuristic audit
EvidenceExperimental dataExpertise and best practices
SpeedSlower (collection)Fast
WhenEnough trafficLow traffic / exploration
RiskStatistical errorSubjective bias

Why it matters for Quebec SMEs

When every ad click is expensive, validating a landing change before scaling protects budget. A/B testing professionalizes CRO even with a few tests per quarter.

FAQ

How much traffic?

Enough to detect the minimum useful effect. Below that, go qualitative.

A/B or multivariate?

A/B first—simpler and more reliable at SME volumes.

Mobile-only tests?

Yes—often the most critical segment.

How long?

At least one or two full business cycles including weekends.

Compliance?

Avoid dark patterns; respect consent and platform policies.

Related terms

Sources and references

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