---
title: "Split test: definition, formula and example"
description: "Showing two versions of an offer to randomly divided visitors over the same period, and comparing what each earns. Also called an A/B test."
url: https://offersuite.io/glossary/split-test
updated: 2026-10-13
---

# Split test

Showing two versions of an offer to randomly divided visitors over the same period, and comparing what each earns. Also called an A/B test.

## In plain words

A split test, or A/B test, shows different versions of an offer to different visitors at the same time. Each visitor is assigned to a version at random and keeps seeing it. The versions are then compared on what they earned.

Randomness and the shared period are what make the comparison fair. Both versions get the same mix of traffic, the same weather, the same ad campaigns. Whatever differs in the result is down to the offer, or to chance, and with enough buyers chance can be ruled out.

## Formula

- Profit per visitor of an arm = the profit of its orders ÷ the visitors assigned to it
- Result = the difference between arms, with an interval around it

## Worked example

The control ships the $40.00 bag free and keeps $15.36 per order. The variant charges $7.00 for shipping and keeps $21.81. The control converts 3.0% of its visitors and the variant 2.3%.

The variant converts worse and wins: $0.50 per visitor against $0.46. By the engine's figure, the control would need 8.9% more buyers to catch up.

### The example order

A $40.00 bag of coffee, shipped free, every cost counted

Revenue $40.00 to contribution margin $15.36 (38.4%)

Revenue

$40.00

Cost of goods

−$12.00

Pick and pack

−$1.18

Packaging

−$0.50

Shipping label

−$7.50

Card fee per order

−$0.30

Refunds

−$2.00

Card processing

−$1.16

Contribution margin

$15.36

2 declared kinds cost nothing on this option

Computed by the margin engine in Offer Suite's own code, in whole cents, from a $40.00 bag of coffee with a $12.00 unit cost.

## A before-and-after comparison is not a split test

Changing an offer and comparing this month with last month mixes the change with everything else that moved: season, ad spend, stock. Only showing both versions over the same days, to visitors divided at random, removes that.

## Using it

Decide the metric before you start, and make it profit per visitor. Run both arms for whole weeks, so each sees the same weekdays. Do not stop the moment one arm is ahead: early leads reverse. And test offers that could plausibly win. A version that needs 40% more buyers to break even is not worth the traffic.

## In Offer Suite

An Offer Suite experiment splits an offer's visitors across arms, where each arm is one version of the offer and the control is the live one. Arms are compared on realized profit per visitor, net of refunds.

Source: Offer Suite's experiment design.

## Related

- [Glossary **Glossary of offer economics** The terms behind offer profit, defined plainly with their formulas and a worked number: contribution margin, profit per visitor, break-even lift and more.](https://offersuite.io/glossary)
- [Calculator **Offer option calculator: profit per visitor** Compare up to three offer options on profit per visitor, margin per order times conversion, and see the conversion lift each one needs to match the best.](https://offersuite.io/calculators/offer-option-profit-per-visitor)
- [Glossary **Profit per visitor: definition, formula and example** The profit an offer earns for every visitor who sees it: margin per order times conversion rate. It weighs a lower price against more buyers fairly.](https://offersuite.io/glossary/profit-per-visitor)
- [Glossary **Conversion rate: definition, formula and example** The share of visitors who buy. An offer test's most reported number and its least sufficient: a better-converting offer can earn less.](https://offersuite.io/glossary/conversion-rate)
- [Glossary **Break-even conversion lift: definition and formula** How much more an offer has to convert to earn, per visitor, what another offer earns: the gap a cheaper offer, a gift or a discount must close.](https://offersuite.io/glossary/break-even-conversion-lift)
- [Glossary **Revenue per visitor: definition and formula** Revenue divided by the visitors who saw an offer: price times conversion. Better than conversion alone, and still blind to what the orders cost.](https://offersuite.io/glossary/revenue-per-visitor)