August 8, 2019
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How many participants do I need for qualitative research?

Optimal Workshop

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!

Publishing date
August 8, 2019
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Tips for recruiting quality research participants

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.

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Dive deeper into participant responses with segments

Our exciting new feature, segments, saves time by allowing you to create and save groups of participant responses based on various filters. Think of it as your magic wand to effortlessly organize and scrutinize the wealth of data and insight you collect in your studies. Even more exciting is that the segments are available in all our quantitative study tools, including Optimal Sort, Treejack, Chalkmark, and Questions.

What exactly are segments?

In a nutshell, segments let you effortlessly create and save groups of participants' results based on various filters, saving you and the team time and ensuring you are all on the same page. 

A segment represents a demographic within the participants who completed your study. These segments can then be applied to your study results, allowing you to easily view and analyze the results of that specific demographic and spot the hidden trends.

What filters can I use?

Put simply, you've got a treasure trove of participant data, and you need to be able to slice and dice it in various ways. Segmenting your data will help you dissect and explore your results for deeper and more accurate results.

Question responses: Using a screener survey or pre - or post-study questions with pre-set answers (like multi-choice), you can segment your results based on their responses.

URL tag: If you identify participants using a unique identifier such as a URL tag, you can select these to create segments.

Tree test tasks, card sort categories created, first click test and survey responses: Depending on your study type, you can create a segment to categorize participants based on their response in the study. 

Time taken: You can select the time taken filter to view data from those who completed your study in a short space of time. This may highlight some time wasters who speed through and probably haven’t provided you with high-quality responses. On the other hand, it can provide insight into A/B tests for example, it could show you if it’s taking participants of a tree test longer to find a destination in one tree or another.

With this feature, you can save and apply multiple segments to your results, using a combination of AND/OR logic when creating conditions. This means you can get super granular insights from your participants and uncover those gems that might have otherwise remained hidden.

When should you use segments?

This feature is your go-to when you have results from two or more participant segments. For example, imagine you're running a study involving both teachers and students. You could focus on a segment that gave a specific answer to a particular task, question, or card sort. It allows you to drill down into the nitty-gritty of your data and gain more understanding of your customers.

How segments help you to unlock data magic 💫

Let's explore how you can harness the power of segments:

Save time: Create and save segments to ensure everyone on your team is on the same page. With segments, there's no room for costly data interpretation mishaps as everyone is singing from the same hymn book.

Surface hidden trends: Identifying hidden trends or patterns within your study is much easier.  With segments,  you can zoom in on specific demographics and make insightful, data-driven decisions with confidence.

Organized chaos: No more data overload! With segments, you can organize participant data into meaningful groups, unleashing clarity and efficiency.

How to create a segment

Ready to take segments for a spin?  To create a new segment or edit an existing one, go to  Results > Participants > Segments. Select the ‘Create segment’ button and select the filters you want to use. You can add multiple conditions, and save the segment.  To select a segment to apply to your results, click on ‘All included participants’ and select your segment from the drop-down menu.  This option will apply to all your results in your study. 


We can't wait to see the exciting discoveries you'll make with this powerful tool. Get segmenting, and let us know what you think! 

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Usability Testing: what, how and why?

Knowing and understanding why and how your users use your product can be invaluable for getting to the nitty gritty of usability. Where they get stuck and where they fly through. Delving deep with probing questions into motivation or skimming over looking for issues can equally be informative.

Usability testing can be done in several ways, each way has its benefits. Put super simply, usability testing literally is testing how useable your product is for your users. If your product isn't useable users will not stick around or very often complete their task, let alone come back for more.

What is usability testing? 🔦

Usability testing is a research method used to evaluate how easy something is to use by testing it with representative users.

These tests typically involve observing a participant as they work through a series of tasks involving the product being tested. Having conducted several usability tests, you can analyze your observations to identify the most common issues.

We go into the three main methods of usability testing:

  1. Moderated and unmoderated
  2. Remote or in person
  3. Explorative, assessment or comparative

1. Moderated or unmoderated usability testing 👉👩🏻💻

Moderated usability testing is done in-person or remotely by a researcher who introduces the test to participants, answers their queries, and asks follow-up questions. Often these tests are done in real time with participants and can involve other research stakeholders. Moderated testing usually produces more in-depth results thanks to the direct interaction between researchers and test participants. However, this can be expensive to organize and run.

Top tip: Use moderated testing to investigate the reasoning behind user behavior.

Unmoderated usability testing is done without direct supervision; likely participants are in their own homes and/or using their own devices to browse the website that is being tested. And often at their own pace.  The cost of unmoderated testing is lower, though participant answers can remain superficial and making follow-up questions can be difficult.

Top tip: Use unmoderated testing to test a very specific question or observe and measure behavior patterns.

2. Research or in-person usability testing 🕵

Remote usability testing is done over the internet or by phone. Allowing the participants to have the time and space to work in their own environment and at their own pace. This however doesn’t give the researcher much in the way of contextual data because you’re unable to ask questions around intention or probe deeper if the participant makes a particular decision. Remote testing doesn’t go as deep into a participant’s reasoning, but it allows you to test large numbers of people in different geographical areas using fewer resources.

Top tip: Use remote testing when a large group of participants are needed and the questions asked can be direct and unambiguous.

In-person usability testing, as the name suggests, is done in the presence of a researcher. In-person testing does provide contextual data as researchers can observe and analyze body language and facial expressions. You’re also often able to converse with participants and find out more about why they do something. However, in-person testing can be expensive and time-consuming: you have to find a suitable space, block out a specific date, and recruit (and often pay) participants.

Top tip: In-person testing gives researchers more time and insight into motivation for decisions.

3. Explorative, Assessment or comparative testing 🔍

These three usability testing methods generate different types of information:

Explorative testing is open-ended. Participants are asked to brainstorm, give opinions, and express emotional impressions about ideas and concepts. The information is typically collected in the early stages of product development and helps researchers pinpoint gaps in the market, identify potential new features, and workshop new ideas.

Assessment research is used to test a user's satisfaction with a product and how well they are able to use it. It's used to evaluate general functionality.

Comparative research methods involve asking users to choose which of two solutions they prefer, and they may be used to compare a product with its competitors.

Top tip: Depending on what research is being done, and how much qualitative or quantitative data is wanted.

Which method is right for you? 🧐

Whether the testing is done in-person, remote, moderated or unmoderated will depend on your purpose, what you want out of the testing, and to some extent your budget. 

Depending on what you are testing, each of the usability testing methods we explored here can offer an answer. If you are at the development stage of a product it can be useful to conduct a usability test on the entire product. Checking the intuitive usability of your website, to ensure users can make the best decisions, quickly. Or adding, changing or upgrading a product can also be the moment to check on a specific question around usability. Planning and understanding your objectives are key to selecting the right usability testing option for your project.

Let's take a look at a couple of examples of usability testing.

1. Lab based, in-person moderated testing - mid-life website

Imagine you have a website that sells sports equipment. Over time your site has become cluttered and disorganized, much like a bricks and mortar store may. You’ve noticed a drop in sales in certain areas. How do you find out what is going wrong or where users are getting lost? Having an in-person, lab (or other controlled environment), moderated usability test with users you can set tasks, watch (and record) what they do.

The researcher can literally be standing or sitting next to the participant throughout, recording contextual information such as how they interacted with the mouse, laptop or even the seat. Watching for cues as to the comfort of the participant and asking questions about why they make decisions can provide richer insights. Maybe they wanted purple yoga pants, but couldn’t find the ‘yoga’ section which was listed under gym rather than a clothing section.

Meaning you can look at how your stock is organised, or even investigate undertaking a card sort. This provides robust and fully rounded feedback on users behaviours, expectations and experiences. Providing data that can directly be turned into actionable directives when redeveloping the website. 

2. Remote, moderated assessment testing - app product development

You are looking at launching an app for parents to access for information and updates for the school. It’s still in development stage and at this point you want to know how easy the app is to use. Setting some very specific set tasks for participants to complete the app can be sent to them and they can be left to complete (or not). Providing feedback and comments around the usability.

The next step may be to use first click testing to see how and where the interface is clicked and where participants may be spending time, or becoming lost. Whilst the feedback and data gathered from this testing can be light, it will be very direct to the questions asked. And will provide data to back up (or possibly not) what assumptions were made.

3. Moderated, In-person, explorative testing - new product development

You’re right at the start of the development process. The idea is new and fresh and the basics are being considered. What better way to get an understanding of what your users’ truly want than an explorative study.

Open-ended questions with participants in a one-on-one environment (or possibly in groups) can provide rich data and insights for the development team. Imagine you have an exciting new promotional app that you are developing for a client. There are similar apps on the market but none as exciting as what your team has dreamt up. By putting it (and possibly the competitors) to participants they can give direct feedback on what they like, love and loathe.

They can also help brainstorm ideas or better ways to make the app work, or improve the interface. All of this done, before there is money sunk in development.

Wrap up 🌯

Key objectives will dictate which usability testing method will deliver the answers to your questions.

Whether it’s in-person, remote, moderated or comparative with a bit of planning you can gather data around your users very real experience of your product. Identify issues, successes and failures. Addressing your user experience with real data, and knowledge can but lead to a more intuitive product.

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