How many participants do I need for qualitative research?

Recruiting high quality participants can be a hassle and time-consuming. That’s why we’ve relaunched Optimal Recruitment with expanded profiling capabilities, enhanced quality controls, and full-service support—to let you focus on what matters most: powerful insights to drive better business outcomes.

‍

What does Optimal Recruitment offer?

With Optimal Recruitment, our in-house team makes it easy to connect with participants. We take care of all the details—from feasibility checks, recruitment, reminders, confirmations, and admin.

‍

Thanks to our four award-winning panel providers, we can tailor recruitment to every recruitment need, giving you access to a vast pool of high-quality participants from across 150+ countries.

• User Interviews: Rated the #1 top-rated panel software on G2, fully dedicated to quality user research
• PureSpectrum: Recognized as the Market Research Supplier of the Year
• Respondent: Ensures a consistent 95% participants show-up rate
• Cint: Winner of the Data Quality Award, 2024

‍

And this is just the beginning—our network will continue to grow, offering even greater targeting capabilities and expanded reach in the future.

‍

How does it work?

All you need to do is provide your participant criteria and our team will handle the rest! We’ll select the best panel for your needs and ensure everything in your study is set up perfectly so you can sit back and watch the results flow in. 
‍

Ready to dive in?

To get started, head over to the Recruit tab under an Optimal study.

‍

Need more info? Find out more about getting started or reach out to Support or your account team for more details.

For those new to the qualitative research space, there’s one question that’s usually pretty tough to figure out, and that’s the question of how many participants to include in a study. Regardless of whether it’s research as part of the discovery phase for a new product, or perhaps an in-depth canvas of the users of an existing service, researchers can often find it difficult to agree on the numbers. So is there an easy answer? Let’s find out.

‍

Here, we’ll look into the right number of participants for qualitative research studies. If you want to know about participants for quantitative research, read Nielsen Norman Group’s article.

‍

‍

Getting the numbers right

‍

So you need to run a series of user interviews or usability tests and aren’t sure exactly how many people you should reach out to. It can be a tricky situation – especially for those without much experience. Do you test a small selection of 1 or 2 people to make the recruitment process easier? Or, do you go big and test with a series of 10 people over the course of a month? The answer lies somewhere in between.

‍

It’s often a good idea (for qualitative research methods like interviews and usability tests) to start with 5 participants and then scale up by a further 5 based on how complicated the subject matter is. You may also find it helpful to add additional participants if you’re new to user research or you’re working in a new area.

‍

What you’re actually looking for here is what’s known as saturation.

‍

‍

Understanding saturation

‍

Whether it’s qualitative research as part of a master’s thesis or as research for a new online dating app, saturation is the best metric you can use to identify when you’ve hit the right number of participants.

‍

In a nutshell, saturation is when you’ve reached the point where adding further participants doesn’t give you any further insights. It’s true that you may still pick up on the occasional interesting detail, but all of your big revelations and learnings have come and gone. A good measure is to sit down after each session with a participant and analyze the number of new insights you’ve noted down.

‍

Interestingly, in a paper titled How Many Interviews Are Enough?, authors Greg Guest, Arwen Bunce and Laura Johnson noted that saturation usually occurs with around 12 participants in homogeneous groups (meaning people in the same role at an organization, for example). However, carrying out ethnographic research on a larger domain with a diverse set of participants will almost certainly require a larger sample.

‍

‍

Ensuring you’ve hit the right number of participants

‍

How do you know when you’ve reached saturation point? You have to keep conducting interviews or usability tests until you’re no longer uncovering new insights or concepts.

‍

While this may seem to run counter to the idea of just gathering as much data from as many people as possible, there’s a strong case for focusing on a smaller group of participants. In The logic of small samples in interview-based, authors Mira Crouch and Heather McKenzie note that using fewer than 20 participants during a qualitative research study will result in better data. Why? With a smaller group, it’s easier for you (the researcher) to build strong close relationships with your participants, which in turn leads to more natural conversations and better data.

‍

There's also a school of thought that you should interview 5 or so people per persona. For example, if you're working in a company that has well-defined personas, you might want to use those as a basis for your study, and then you would interview 5 people based on each persona. This maybe worth considering or particularly important when you have a product that has very distinct user groups (e.g. students and staff, teachers and parents etc).

‍

‍

How your domain affects sample size

‍

The scope of the topic you’re researching will change the amount of information you’ll need to gather before you’ve hit the saturation point. Your topic is also commonly referred to as the domain.

‍

If you’re working in quite a confined domain, for example, a single screen of a mobile app or a very specific scenario, you’ll likely find interviews with 5 participants to be perfectly fine. Moving into more complicated domains, like the entire checkout process for an online shopping app, will push up your sample size.

‍

As Mitchel Seaman notes: “Exploring a big issue like young peoples’ opinions about healthcare coverage, a broad emotional issue like postmarital sexuality, or a poorly-understood domain for your team like mobile device use in another country can drastically increase the number of interviews you’ll want to conduct.”

‍

‍

In-person or remote

‍

Does the location of your participants change the number you need for qualitative user research? Well, not really – but there are other factors to consider.

‍

• Budget: If you choose to conduct remote interviews/usability tests, you’ll likely find you’ve got lower costs as you won’t need to travel to your participants or have them travel to you. This also affects…
• Participant access: Remote qualitative research can be a lifesaver when it comes to participant access. No longer are you confined to the people you have physical access to — instead you can reach out to anyone you’d like.
• Quality: On the other hand, remote research does have its downsides. For one, you’ll likely find you’re not able to build the same kinds of relationships over the internet or phone as those in person, which in turn means you never quite get the same level of insights.

‍

‍

Is there value in outsourcing recruitment?

‍

Recruitment is understandably an intensive logistical exercise with many moving parts. If you’ve ever had to recruit people for a study before, you’ll understand the need for long lead times (to ensure you have enough participants for the project) and the countless long email chains as you discuss suitable times.

‍

Outsourcing your participant recruitment is just one way to lighten the logistical load during your research. Instead of having to go out and look for participants, you have them essentially delivered to you in the right number and with the right attributes.

‍

We’ve got one such service at Optimal Workshop, which means it’s the perfect accompaniment if you’re also using our platform of UX tools. Read more about that here.

‍

‍

Wrap-up

‍

So that’s really most of what there is to know about participant recruitment in a qualitative research context. As we said at the start, while it can appear quite tricky to figure out exactly how many people you need to recruit, it’s actually not all that difficult in reality.

‍

Overall, the number of participants you need for your qualitative research can depend on your project among other factors. It’s important to keep saturation in mind, as well as the locale of participants. You also need to get the most you can out of what’s available to you. Remember: Some research is better than none!

If there’s one universal truth in user research, it’s that at some point you’re going to need to find people to actually take part in your studies. Be it a large number of participants for quantitative research or a select number for in-depth, in-person user interviews. Finding the right people (and number) of people can be a hurdle.

‍

With the right strategy, you can source exactly the right participants for your next research project.

‍

We share a practical step-by-step guide on how to find participants for user experience research.

‍

The difficulties/challenges of user research recruiting 🏋️

‍

It has to be acknowledged that there are challenges when recruiting research participants. You may recognize some of these:

‍

• There are so many channels and methods you can use to find participants, different channels will work better for different projects.
• Repeatedly using the same channels and methods will result in diminishing returns (i.e. burning out participants).
• It’s a lengthy and complex process, and some projects don’t have the luxury of time.
• Offering the right incentives and distributing them is time-consuming.
• It’s hard to manage participants during long-term or recurring studies, such as customer research projects.

‍

We’ll simplify the process, talk about who the right participants are, and unpack some of the best ways to find them. Removing these blocks can be the easiest way to move forward.

‍

Who are the right participants for different types of research? 🤔

‍

1. The first step to a successful participant recruitment strategy is clarifying the goals of your user research and which methods you intend to use. Ask yourself:

• What is the purpose of our research?
• How do we plan to understand that?

‍

2. Define who your ideal research participant is. Who is going to have the answers to your questions?

‍

3. Work out your research recruitment strategy. That starts by understanding the differences between recruiting for qualitative and quantitative research.

‍

Recruiting for qualitative vs. quantitative research 🙋🏻

‍

Quantitative research recruiting is a numbers game. For your data analysis to be meaningful and statistically significant, you need a lot of data. This means you need to do a lot of research with a lot of people. When recruiting for quantitative research, you first have to define the population (the entire group you want to study). From there, you choose a sampling method that allows you to create a sample—a randomly selected subset of the population who will participate in your study.

‍

Qualitative recruiting involves far fewer participants, but you do need to find a selection of ‘perfect’ participants. Those that fit neatly into your specific demographic, geographic, psychographic, and behavioral criteria relevant to your study. Recruiting quality participants for qualitative studies involves non-random sampling, screening, and plenty of communication.

‍

How many participants do you need? 👱🏻👩👩🏻👧🏽👧🏾

‍

How many participants to include in a qualitative research study is one of the most heavily discussed topics in user research circles. In most cases, you can get away with 5 people – that’s the short answer. With 5 people, you’ll uncover most of the main issues with the thing you’re testing. Depending on your research project there could be as many as 50 participants, but with each additional person, there is an additional cost (money and time).

‍

Quantitative research is obviously quite different. With studies like card sorts and tree tests, you need higher participant numbers to get statistically meaningful results. Anywhere from 20 - 500 participants, again coming back to the purpose of your test and your research budget. These are usually easier and quicker to implement therefore the additional cost is lower.

‍

User research recruitment - step by step 👟

‍

Let’s get into your research recruitment strategy to find the best participants for your research project. There are 5 clear steps to get you through to the research stage:

‍

1. Identify your ideal participants

‍

Who are they? What do they do? How old are they? Do they already use your product? Where do they live? These are all great questions to get you thinking about who exactly you need to answer your research questions. The demographic and geographic detail of your participants are important to the quality of your research results.

‍

2. Screen participants

‍

Screening participants will weed out those that may not be suitable for your specific project. This can be as simple as asking if the participants have used a product similar to yours. Or coming back to your key identified demographic requirements and removing anyone that doesn’t fit these criteria.

‍

3. Find prospective participants

‍

This is important and can be time-consuming. For qualitative research projects, you can look within your organization or ask over social media for willing participants. Or if you’re short on time look at a participant recruitment service, which takes your requirements and has a catalog of available persons to call on. There’s a cost involved, but the time saving can negate this. For qualitative surveys, a great option can be a live intercept on your website or app that interrupts users and asks them to complete a short questionnaire.

‍

4. Research incentives

‍

In some cases you will need to provide incentives. This could be offering a prize or discount for those who complete online qualitative surveys. Or a fixed sum for those that take part in longer format quantitative studies.

‍

5. Scheduling with participants

‍

Once you have waded through the emails, options, and communication from your inquiries make a list of appropriate participants. Schedule time to do the research, either in person or remotely. Be clear about expectations and how long it will take. And what the incentive to take part is.

‍

Tips to avoid participant burnout 📛

‍

You’ve got your participants sorted and have a great pool of people to call on. If you keep hitting the same group of people time and time again, you will experience the law of diminishing returns. Constantly returning to the same pool of participants will eventually lead to fatigue. And this will impact the quality of your research because it’s based on interviewing the same people with the same views.

‍

There are 2 ways to avoid this problem:

‍

1. Use a huge database of potential participant targets.
2. Use a mixture of different recruitment strategies and channels.

‍

Of course, it might be unavoidable to hit the same audience repeatedly when you’re testing your product development among your customer base.

‍

Wrap up 🌯

‍

Understanding your UX research recruitment strategy is crucial to recruiting quality participants. A clear idea of your purpose, who your ideal participants are, and how to find them takes time and experience. 

‍

And to make life easier you can always leave your participant recruitment with us. With a huge catalog of quality participants all at your fingertips on our app, we can recruit the right people quickly.

‍

Check out more here.