Speed, Quality, and Flexibility: Optimizing Your User Research Recruitment

A well-maintained participant panel is more than a time-saver. It sets your team up for better research from day one. The people you recruit and how you track, segment, and manage those relationships over time directly shapes how reliable your findings are.  

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With the right setup in place, you can move forward with confidence, knowing that these participants meet your criteria, aren’t overused, and can bring fresh perspectives to each study.

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Tools like Rally UXR bring that structure to participant recruitment. It helps you build and manage your own participant panel, keep track of consent and contact history, coordinate logistics, and stay on top of all the moving parts. You can also see things like incentive history and email engagement, making it much easier to decide who to invite and when.

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But recruitment is just the starting point. The real value comes next: running the research and turning participant feedback into insights you can actually use.

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Using Rally + Optimal together

Whether you’re running unmoderated studies, testing designs, navigation, or content, or conducting usability testing calls, having the right research tools in place is critical. If you’re already using Rally, pairing it with Optimal can connect the dots from recruitment through to insights, without adding friction to your workflow.
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You can also use Optimal’s on-demand or custom managed recruitment services, though Rally’s strength lies in building your own custom panel and database.
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Here’s how to combine Rally and Optimal into a smooth, efficient research workflow.
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Start with intentional recruitment

Define your participant criteria in Rally. Use screening questions not just to qualify participants. Think beyond “does this person qualify?” and start building segments you can reuse: power users vs. casual users, returning users vs. first-timers, people familiar with the old design vs. new. These segments can make it easier to run focused studies and compare results over time.

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Build your study in parallel

A simple shift that makes a big difference: don’t wait. Build your study in Optimal before sending invites from Rally. This ensures that when participants are ready, the link can be dropped into Rally, and distribution happens the moment you're ready.

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Use the strengths of each platform

Rally handles the relationship and profile management: who's been invited, who's confirmed, who needs a reminder, screener and survey history, consent forms, and more. Optimal handles the research: collecting quantitative and qualitative data, visualising patterns, quantifying usability issues, automating insights with AI, and surfacing the metrics and insights that actually answer your research question. 

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With Optimal, you can immediately put Rally-recruited participants into studies including:
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• Prototype testing
• Live site testing 
• Card sorting
• Tree testing
• First-click testing
• Surveys
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Keep your insights in one place‍‍

When it comes to research, scattered insights = lost impact. Using Optimal as your central hub for results, recordings, and analysis makes it easier to share findings with your team and stakeholders, track progress over time, and back up decisions with real evidence. 
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The tools you use for recruitment and the tools you use for research aren't just operational choices. They shape your research culture. When recruitment and research are both well-structured, everything runs more smoothly. Teams that invest in structure on both ends of the workflow tend to produce research that's faster, more credible, and more likely to influence decisions. 
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Rally and Optimal are powerful on their own. Together, they create a workflow that’s scalable, insight-driven, and built for continuous discovery.

If you're not yet using Optimal, you can start a free trial or book a demo.

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.

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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.

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Getting the numbers right

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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.

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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.

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

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Understanding saturation

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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.

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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.

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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.

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Ensuring you’ve hit the right number of participants

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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.

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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.

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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).

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How your domain affects sample size

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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.

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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.

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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.”

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In-person or remote

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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.

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• 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.

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Is there value in outsourcing recruitment?

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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.

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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.

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

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Wrap-up

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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.

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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!

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.

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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.

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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

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

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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. 
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Ready to dive in?

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

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