How many participants do I need for qualitative research?

We recently hosted a live webinar introducing Optimal's new Usability Testing tool, a powerful solution that brings multiple research methods together in a single study, helping you get better insights, faster.

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Looking for the highlights? We've rounded up answers to the most common questions from the session.

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What is Usability Testing?

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Optimal's new Usability Testing tool is a mixed-methods research tool that brings Prototype Testing, Live Site Testing, and Surveys into a single, end-to-end study workflow. Instead of treating each method as its own initiative, you can combine them inside a single study to allow participants to move naturally between tasks, experiences, and questions.

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With this tool, you can compare multiple prototypes side by side, benchmark a current live experience against a redesigned concept, evaluate a competitor's experience, and more. And researchers get everything analyzed in one place with AI-powered summaries, task results, video clips, and evidence-backed insights surfaced automatically.

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Is Usability Testing supported for mobile testing?

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Yes, participants can complete Usability Testing studies on mobile devices using their mobile browser or the Optimal Participant App. If screen recording is required, participants are prompted to download the Optimal Participant App, available for both iOS and Android. 

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Do you have to use multiple methods, or can you run just one?

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You can keep it simple and run a single survey, a standalone prototype test, or a live site session on its own. Or, mix methods or run multiple of the same method, such as multiple prototypes or live website tests in one study. The tool supports however your study needs to be shaped.

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Can you run bilingual studies?

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Usability Testing currently supports over 30 languages enabling what participants see and guiding how AI models interpret responses, generate summaries, identify themes, and surface insights. Today, studies are configured around a single language, so participants are expected to respond in the chosen language. That said, multilingual study support is something we're exploring for our roadmap.

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Are participants recruited once across all methods, or separately for each?

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Just once. From the participant's perspective, this looks and feels like a single study regardless of how many methods are included. They move through the experience naturally from start to finish.

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To what extent can sections and questions be randomized?

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Section-level randomization shuffles the order of any sections, while question-level randomization works within a specific section, shuffling the order of tasks and follow-up questions. Both are supported, giving researchers the flexibility to reduce order bias, particularly useful when comparing multiple experiences.

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Can you test multiple prototypes within the same study?

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Yes, with no limitations on the number of prototypes you can link to a single study so you can add multiple Figma prototype sections and connect a different prototype to each one.

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Can you reorder sections and questions in a study?

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Given that Usability Testing studies can grow complex, the ability to reorder things quickly was a priority. You can reorder individual tasks and questions within a section, and sections themselves by dragging them in the Build panel.

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How effectively can Usability Testing scale across a business?

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Scaling research isn't just about running more studies, it's about helping more people across the business access insights, understand them, and use them to make decisions. With Usability Testing, product managers, designers, and stakeholders can quickly understand what happened and why without having to see hours of recording through the automatically generated highlight reels, key quotes, and transcripts.

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Watch the full webinar

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If you want to experience the full walkthrough, demo, and Q&A, watch the recording to see Usability Testing in action and pick up tips and best practices straight from the session.

👉 Watch the full webinar here.

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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.

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

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

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The difficulties/challenges of user research recruiting 🏋️

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

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• 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.

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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.

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

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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?

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

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

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Recruiting for qualitative vs. quantitative research 🙋🏻

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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.

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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.

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

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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).

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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.

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User research recruitment - step by step 👟

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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:

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1. Identify your ideal participants

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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.

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2. Screen participants

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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.

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3. Find prospective participants

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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.

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4. Research incentives

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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.

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5. Scheduling with participants

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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.

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Tips to avoid participant burnout 📛

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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.

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There are 2 ways to avoid this problem:

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

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

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Wrap up 🌯

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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. 

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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.

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Check out more here.

Recruiting the right participants is one of the biggest challenges teams face when conducting user research. Poor quality or disengaged testers can lead to unreliable data. While bottlenecks in recruitment – long lead times and limited access – can delay studies, reduce research frequency, and slow product development. 

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Having flexible options helps you keep moving at pace. Whether you bring your own participants, use Optimal’s recruitment services, or leverage external panel providers, Optimal gives you the flexibility to recruit the right user testers consistently and efficiently so you can launch studies faster, run them more frequently, and quickly scale research across multiple projects.

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Here’s a breakdown of your recruitment options with Optimal:

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1.  Invite Your Own Participants For Free

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Optimal lets you invite your own participants with a study link, QR code, or intercept snippet at no extra cost, giving you full control over who takes part in your studies.

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2. Use Any Panel Provider You Prefer

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Optimal works seamlessly with any panel provider, such as User Interviews, Respondent, PureSpectrum, Prolific, Dynata, Askable, and Cint.

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How it works:

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1. Create and publish an unmoderated study in Optimal, such as a live site test, prototype test, survey, first-click test, card sort or tree test.
2. Specify your audience criteria in the panel platform.
3. Add screener questions in your panel provider and/or Optimal.
4. Add your Optimal study link into the panel provider platform.
5. Panel provider recruits participants and manages incentives.
6. See a participant list in Optimal and review participant metrics like completion rate, time taken, and location breakdown.
7. Optional: Create segments in Optimal for more targeted insights.
8. Review insights, results, and analytics in Optimal to make informed research decisions.

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Certain panel providers, like User Interviews, offer additional benefits through direct integration with Optimal. You can automate participant tracking and see participant status in real time in your panel provider platform as user testers complete your studies.

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3. Use Optimal’s Specialized Recruitment Services

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For teams that want expert support, Optimal Recruitment support taps into multiple panels to access over 20 million participants across 150 countries. Whether you're looking for a broad audience or something highly specific, we can help you find the right people to take part in your study.

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Optimal handles the panel selection, incentive management, and criteria refinement. We’ll even review and optimize your screener questions. Get started by submitting your criteria. 

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4. Use Optimal’s Recruitment Panel

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Looking for another quick recruitment solution? You can order user testers instantly inside the Optimal platform. It’s ideal for B2C research and studies with basic demographic requirements, and Optimal takes care of incentives for you.

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Recruitment Flexibility and Quality

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You’re never locked into a single approach with Optimal. Instead, you can adapt your recruitment strategy to each study, balancing speed, quality, budget, and scale, while using the same research and user insights platform.

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From shareable study links to easy panel workflows and expert support when you need it, you can spend less time managing recruitment and more time gathering actionable user insights.