Comprehensive Guide on A/B Testing for Beginners

Published on November 6th, 2023

13 min read

What is A/B Testing?

A/B testing, or split testing, is a research technique widely used in marketing, web development, and user experience (UX) fields. This method involves comparing two versions of an element, such as a web page or advertisement, to determine which performs better regarding desired outcomes.

Within the framework of A/B testing, researchers designate these versions as “A,” “B,” “C,” and so forth. These variants are then simultaneously tested among similar audiences, allowing researchers to assess their effectiveness and influence on user behavior.

A/B testing empowers marketers, designers, and developers to make informed decisions backed by data, improving awareness, click-through rates, and conversions. Conducting A/B tests on entire web pages or specific components like images and layouts is possible.

This technique finds applications in various areas, including:

  • Crafting subject lines for email marketing
  • Formatting content to optimize engagement
  • Enhancing the impact of call-to-action (CTA) buttons
  • Optimizing the placement of advertisements

Example of A/B Testing

Imagine this scenario: You’ve developed an email marketing campaign to spark interest in a new line of products.

For the initial message, you’ve devised two distinct subject lines labeled version A and version B.

From a sizable email list of 5,000 individuals, you’ve selected a representative sample of 500 recipients.

Out of this group, you’ve directed version A of the subject line to 250 individuals, while the remaining 250 individuals receive version B.

Upon completing the test, the collected data revealed that 68 recipients opened the email featuring version B, whereas only 37 engaged with version A.

Based on this outcome, you deduce that version B holds more significant potential for capturing your audience’s attention, prompting you to adopt it for the broader campaign.

In this process, you’ve effectively executed an A/B test.

Why A/B Tests Work?

A/B testing eliminates the uncertainties tied to marketing campaigns, changes to websites, and the optimization of conversion rates (CRO).

A/B Testing helps you to:

  • Enhance the utility of existing traffic: Traffic that does not translate into conversions holds limited value for most businesses. Developing the most optimal version of your website heightens the likelihood of visitors making purchases, subscribing, or maintaining engagement.
  • Decrease bounce rates: Captivate fresh visitors so they prolong their stay on your website. The longer their engagement, the greater the chance they will acquaint themselves with your brand and perceive you as a solution to their needs.
  • Boost sales: Fine-tune marketing campaigns to attract ideal customers for your business (those most predisposed to making purchases and cultivating loyalty), achieving heightened conversion rates.
  • Attain insights about your audience: Utilize test outcomes to comprehend what resonates and what falls short with your intended audience. Integrate these insights into future endeavors involving website design and marketing strategies.

However, you only get these results in the case of well-executed A/B tests. An accurate implementation could result in saving time and opportunities for generating sales.

What are the Places Where You Can Do A/B Testing?

Utilizing A/B testing enables you to fine-tune a range of factors, from the intricate components of your website layout to the attention-grabbing points in your email subject lines.

Below are some of the most important tests that you should consider conducting.

Calls to Action (CTAs)

Having a compelling Call to Action (CTA) can be the difference between someone taking action, like purchasing your product or subscribing to your email newsletter, and them going to your competitors.

A/B testing allows you to experiment with different aspects of your CTAs, such as:

  1. Copy: After your content has presented its case, a catchy closing line can be what encourages visitors to take that step.
  1. Placement: Your CTA should be noticeable but not so prominent that it distracts from your main message—let people absorb that first.
  1. Size: The CTA needs to be a good size to catch clicks (or taps) without becoming a distraction.
  1. Design: Is your CTA a standout button or just a link blended into your text? Both approaches have their merits—A/B testing helps you determine what works better for your audience.
  1. Font: Going for a completely different font might be jarring, especially if your CTA is part of your content. But trying out a few designs could be insightful if it’s a button.

The main aim of a CTA is to encourage action, usually leading to a conversion. You can measure the impact of any changes you make using these two metrics:

  1. Click-through Rate (CTR): This is the ratio of the number of clicks on your CTA to the number of times people see it. For instance, if 100 people land on a page and five click the CTA button, the CTR is 5%.
  1. Conversion Rate: This is the percentage of visitors who complete the desired action—requesting a quote, joining your mailing list, or making a purchase.

You’ll often encounter CTAs at the bottom of products and other landing pages. You can also test CTAs in search engine ads, social media ads, and marketing emails.


The headline is the first thing that catches your visitors’ eyes when they land on your webpage. Whether it is grabbing attention or not determines whether they stay or move on. That’s why it’s a prime candidate for A/B testing.

For best results, keep these pointers in mind when crafting your headlines:

  1. Keep it short. Ideally, aim for around six to eight words. You might not always hit this mark, but it’s a helpful exercise to evaluate the value and impact of each word.
  2. Be direct. Your headline is your first impression. Ensure it snags attention right away.
  3. Make it catchy. Memorable headlines make your content more shareable, and content that’s easy to share boosts your brand’s visibility. Use literary tools like alliteration, rhymes, assonance, etc.
  4. Mirror your content. Leading your readers astray can lead them to bounce off your page and never return. Your content should deliver the promise your headline made.

Give A/B testing a shot by experimenting with different versions of your headlines. Play around with various styles like fonts, sizes, colors, and different word choices and messaging.

If you’re working on your website content, you can use the following metrics to measure the impact of your changes:

  1. Page views: This tells you how often a specific page on your website was visited. A more vital headline should naturally attract more views.
  2. Average time on page: This is the average amount of time visitors spend on a page. If your headlines are clear, this number might be higher.
  3. Bounce rate: This represents the percentage of people who land on a page and leave without taking any specific action. A higher bounce rate could suggest that your headline is engaging, but your content needs to match up.
  4. Dwell time: This is the duration users remain on a page after finding it in search results before returning to the search results page. If dwell time is short, it could indicate that your headline and metadata are compelling, but your content might need to be revised.

You can find all these content marketing metrics and more using Google Analytics.

Email Subject Lines

Think of the subject line as the headline of your email—it’s the thing that decides if people will open your message.

Believe it or not, even tiny changes can affect how many folks actually open your email. So, don’t just go with the first subject line that pops into your head. Instead, jot down about 10 or more ideas. After that, put your top contenders to the test with some A/B testing. Send them out to smaller groups and see which one performs best.

A good subject line should grab the attention and curiosity of folks reading their emails. But remember, it needs to stand out without leading readers astray. So, focus on the main benefit of your email and talk to your audience in a way that makes sense to them—use their language and a tone that clicks.

Let’s review some smart approaches for crafting email subject lines:

  1. Use numbers when they fit. They often boost open rates.
  2. Ask questions. This can spark curiosity among email recipients, making them more likely to open your email.
  3. Steer clear of worn-out phrases. Lines like “open for a surprise,” “discover a fantastic deal,” and “try our product for free” have been seen too often.

Now, why does this all matter? In nearly every scenario, your subject line’s main job is to grab attention and get people to open your email. So, when you’re comparing different versions of a subject line in an A/B test, you can choose the one that scores the highest open rate.

Website Layout

Want to make it super easy for your users to convert? Just make sure the stuff they want and need is front and center.

You might have two pages with the same info. But if one looks messy or focuses on the less important stuff, it will be less attractive to visitors.

For example, the homepage of Autosoft DMS, one of our clients, opens with a short, snappy, interactive illustration to create intrigue. About 90% of the people in the US are right-handed. That’s why the form is on the right side of the page.

Clicking on the watch video button on the left-hand side of the web page will open a window with a short one-minute product trailer. And as countless marketing studies have shown, videos help visitors convert better than just having text; this is a great strategy. 

However, everything we have discussed so far about these web pages is subject to A/B testing, from the headline to the positioning of CTAs to the text on those CTAs. Maybe two CTAs are too much for the users, and maybe the video should play automatically in the background. You will never know unless you implement and test.

Right after this section, there are screenshots of what the product looks like from the inside. Since B2B SaaS tools have a higher ticket pricing than B2C, showing product screenshots reassures buyers of the quality of the product. 

The headline, the screenshots used, and the CTAs are subject to A/B testing. PS: The website’s current layout was finalized after thorough A/B testing already.

When your page is all jumbled up and not making sense, you’ll likely see:

  • High bounce rates
  • Low conversion rates
  • Low average time on page
  • Low dwell times

If you’ve got a designer on your team, they’ll have the scoop on how to arrange things in a good way. But if not, think about what your users really want. That way, you can put the coolest and most helpful stuff right where they can find it easily.

This is why, for all our SaaS clients for Conversion Rate Optimization and Digital Advertising servicing, we recommend creating 3-4 different layouts for the landing pages.

How to Run Your First A/B Test?

Ready to give A/B testing a shot? Follow this step-by-step guide to run a basic A/B test in seven straightforward steps:

  1. Start by spotting opportunities for improvement. Analyze your website’s performance using tools like Semrush, Google Analytics, and Google Search Console. These tools can reveal areas that might need some refining.
  1. Choose a variable to test. Instead of juggling multiple changes, focus on one element at a time. For instance, if shorter headlines seem more effective, that could be your focus.
  1. Define your test hypothesis. Clarify what you’re trying to learn. Remember, A/B tests are about proving or disproving ideas with data. For example, you could hypothesize that “shorter headlines are more engaging than longer ones.”
  1. Set goals and test duration. Pick a primary metric you’ll measure. Choose a specific test period, usually around a month, to run your test.
  1. Create variations. Set up your “control” version (unchanged) and the “challenger” version (the one with changes). For minor variables, copy the existing content and tweak the details.
  1. Run your test. Use a 302 redirect to send users to the challenger page temporarily. This ensures accurate results, especially for search engine testing.
  1. Analyze and plan. After your test period, compare the results of both versions. If the new version performs better, apply what you’ve learned to other parts of your site. If not, don’t worry—it’s a chance to improve.

Remember, even if your hypothesis doesn’t hold up, every result teaches something new. Use these learnings to come up with fresh testing ideas.

Pushkar Sinha

Pushkar is a Digital Marketing Manager and leads SEO Research at FirstPrinciples Growth Advisory. He has over 12 years of experience in Search Engine Optimization for European, American, and Indian markets, both from the agency and as in-house marketing support.

Over these years, he has helped startups and multinational companies (Finance, NBFC, SaaS, Home Improvement, Health, and Software) grow their organic search visibility & achieve their SEO goals.

He is an innovative, cross-functional marketing leader with a track record of planning and managing exceptional marketing campaigns yielding positive returns.

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