A/B testing for membership sites

A/B testing means showing two versions of something, such as a headline, a sales page or an email, to different groups of people at the same time and seeing which performs better. Done well, it replaces opinion with evidence. Done badly, it produces confident conclusions from what was really just chance.

Websites with enormous traffic can test tiny changes and get clear answers. Most membership sites cannot. With a few thousand visitors a month and a few dozen sign-ups, you need a different approach: fewer tests, bigger changes, clear rules and honest reading of the results.

Why modest traffic changes everything

The problem is noise. Sign-ups vary from week to week for reasons that have nothing to do with your page: a mention in someone's newsletter, a holiday, a busy week in your members' working lives. When you split your traffic in two, each version gets half the visitors and a handful of sign-ups, and random variation can easily make one look better.

Think of flipping a coin. Flip it ten times and getting seven heads is not unusual. Flip it a thousand times and getting seven hundred heads would be astonishing. Small numbers of sign-ups behave like the ten flips: a difference of three or four members between versions tells you very little.

That does not make testing pointless. It means designing tests that can produce a clear answer with the traffic you have.

Test changes big enough to matter

With modest traffic, tweaking a button color is a waste of time, because any difference will be too small to detect. Test changes that could plausibly make a large difference to how people understand your offer:

• A completely different headline that makes a different promise.
• A short sales page against a long one.
• Annual pricing shown first against monthly pricing shown first.
• A free trial against a money-back guarantee.
• A video at the top of the page against none.

Here is a headline pair a hypothetical meditation membership might test:

Version A: Guided meditations for every part of your day

Version B: Ten minutes a day to feel calmer at work, with guidance from a real teacher

These make genuinely different promises, so if one works better, the difference has a chance of being large enough to see. For more on what makes the page itself persuasive, see a sales page that answers the real questions.

Test where the traffic is

Run tests on your highest-traffic pages and your largest sends. For most membership sites, that means the home page, the sales or pricing page, and emails to your full list.

Email is often the easiest place to learn, because you can send two versions to two halves of a list at once, and every recipient sees one version. Just remember that more opens are only worth having if the email then does its job; see writing subject lines people open.

Set the rules before you start

Most false conclusions come from making up the rules along the way: stopping when one version pulls ahead, or changing what counts as success. Decide these in advance and write them down:

1. One change. The two versions differ in one clear way, even if that way is big.
2. One success measure. Usually completed sign-ups, not clicks or time on page.
3. A fixed duration. Run for whole weeks, at least two and often four or more, so weekday and weekend patterns balance out.
4. A minimum count. In our experience, waiting until each version has at least several dozen sign-ups is a sensible floor before reading much into a difference. With fewer than that, chance dominates.
5. A decision rule. What difference would make you switch? If the result is too close to call, which version will you keep?

Reading results honestly

Suppose the meditation membership runs its headline test for four weeks on a sales page that gets about 3,000 visitors in that time. Illustrative results:

• Version A: 1,500 visitors, 30 sign-ups.
• Version B: 1,500 visitors, 42 sign-ups.

Version B looks better, and with a gap of twelve sign-ups on these numbers it may well be. But it is not certain. A reasonable response is to switch to Version B, keep watching the conversion rate over the following months, and treat the result as promising rather than proven. If the result had been 30 against 33, the honest conclusion would be that the test showed no clear difference, and either version is fine.

Before trusting any result, check whether the members from each version stay. A headline that overpromises may win sign-ups and lose members at their first renewal. If you can, follow both groups for a couple of months. Looking at the whole journey, as in conversion rates from visitor to member, keeps you from celebrating a win at one stage that becomes a loss at the next.

When you cannot A/B test

Some pages simply do not get enough traffic, and some changes, such as a price rise, are hard to split fairly. Alternatives:

• Watch real people. Ask five people from your audience to use the page while thinking aloud. You will learn more about confusion in an hour than a test could show in months.
• Ask non-joiners. A short question to people who visited your pricing page but did not join often reveals the real objection.
• Change, then compare carefully. Make a change and compare against a fair baseline, watching for anything else that could explain a difference.

Your first test

1. Pick your highest-traffic page or your largest email list.
2. Choose one bold change that could make a real difference.
3. Write down the success measure, duration, minimum count and decision rule.
4. Run the test for the full duration without peeking and stopping early.
5. Record the result, including an honest note if it was inconclusive, and check how well each group's members stay afterward.