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

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!

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Usability Experts Unite: The Power of Heuristic Evaluation in User Interface Design

Usability experts play an essential role in the user interface design process by evaluating the usability of digital products from a very important perspective - the users! Usability experts utilize various techniques such as heuristic evaluation, usability testing, and user research to gather data on how users interact with digital products and services. This data helps to identify design flaws and areas for improvement, leading to the development of user-friendly and efficient products.

Heuristic evaluation is a usability research technique used to evaluate the user interface design of a digital product based on a set of ‘heuristics’ or ‘usability principles’. These heuristics are derived from a set of established principles of user experience design - attributed to the landmark article “Improving a Human-Computer Dialogue” published by web usability pioneers Jakob Nielsen and Rolf Molich in 1990. The principles focus on the experiential aspects of a user interface. 

In this article, we’ll discuss what heuristic evaluation is and how usability experts use the principles to create exceptional design. We’ll also discuss how usability testing works hand-in-hand with heuristic evaluation, and how minimalist design and user control impact user experience. So, let’s dive in!

Understanding Heuristic Evaluation


Heuristic evaluation helps usability experts to examine interface design against tried and tested rules of thumb. To conduct a heuristic evaluation, usability experts typically work through the interface of the digital product and identify any issues or areas for improvement based on these broad rules of thumb, of which there are ten. They broadly cover the key areas of design that impact user experience - not bad for an article published over 30 years ago!

The ten principles are:

  1. Prevention error: Well-functioning error messages are good, but instead of messages, can these problems be removed in the first place? Remove the opportunity for slips and mistakes to occur.
  2. Consistency and standards: Language, terms, and actions used should be consistent to not cause any confusion.
  3. Control and freedom for users: Give your users the freedom and control to undo/redo actions and exit out of situations if needed.
  4. System status visibility: Let your users know what’s going on with the site. Is the page they’re on currently loading, or has it finished loading?
  5. Design and aesthetics: Cut out unnecessary information and clutter to enhance visibility. Keep things in a minimalist style.
  6. Help and documentation: Ensure that information is easy to find for users, isn’t too large and is focused on your users’ tasks.
  7. Recognition, not recall: Make sure that your users don’t have to rely on their memories. Instead, make options, actions and objects visible. Provide instructions for use too.
  8. Provide a match between the system and the real world: Does the system speak the same language and use the same terms as your users? If you use a lot of jargon, make sure that all users can understand by providing an explanation or using other terms that are familiar to them. Also ensure that all your information appears in a logical and natural order.
  9. Flexibility: Is your interface easy to use and it is flexible for users? Ensure your system can cater to users to all types, from experts to novices.
  10. Help users to recognize, diagnose and recover from errors: Your users should not feel frustrated by any error messages they see. Instead, express errors in plain, jargon-free language they can understand. Make sure the problem is clearly stated and offer a solution for how to fix it.

Heuristic evaluation is a cost-effective way to identify usability issues early in the design process (although they can be performed at any stage) leading to faster and more efficient design iterations. It also provides a structured approach to evaluating user interfaces, making it easier to identify usability issues. By providing valuable feedback on overall usability, heuristic evaluation helps to improve user satisfaction and retention.

The Role of Usability Experts in Heuristic Evaluation

Usability experts play a central role in the heuristic evaluation process by providing feedback on the usability of a digital product, identifying any issues or areas for improvement, and suggesting changes to optimize user experience.

One of the primary goals of usability experts during the heuristic evaluation process is to identify and prevent errors in user interface design. They achieve this by applying the principles of error prevention, such as providing clear instructions and warnings, minimizing the cognitive load on users, and reducing the chances of making errors in the first place. For example, they may suggest adding confirmation dialogs for critical actions, ensuring that error messages are clear and concise, and making the navigation intuitive and straightforward.

Usability experts also use user testing to inform their heuristic evaluation. User testing involves gathering data from users interacting with the product or service and observing their behavior and feedback. This data helps to validate the design decisions made during the heuristic evaluation and identify additional usability issues that may have been missed. For example, usability experts may conduct A/B testing to compare the effectiveness of different design variations, gather feedback from user surveys, and conduct user interviews to gain insights into users' needs and preferences.

Conducting user testing with users that represent, as closely as possible, actual end users, ensures that the product is optimized for its target audience. Check out our tool Reframer, which helps usability experts collaborate and record research observations in one central database.

Minimalist Design and User Control in Heuristic Evaluation

Minimalist design and user control are two key principles that usability experts focus on during the heuristic evaluation process. A minimalist design is one that is clean, simple, and focuses on the essentials, while user control refers to the extent to which users can control their interactions with the product or service.

Minimalist design is important because it allows users to focus on the content and tasks at hand without being distracted by unnecessary elements or clutter. Usability experts evaluate the level of minimalist design in a user interface by assessing the visual hierarchy, the use of white space, the clarity of the content, and the consistency of the design elements. Information architecture (the system and structure you use to organize and label content) has a massive impact here, along with the content itself being concise and meaningful.

Incorporating minimalist design principles into heuristic evaluation can improve the overall user experience by simplifying the design, reducing cognitive load, and making it easier for users to find what they need. Usability experts may incorporate minimalist design by simplifying the navigation and site structure, reducing the number of design elements, and removing any unnecessary content (check out our tool Treejack to conduct site structure, navigation, and categorization research). Consistent color schemes and typography can also help to create a cohesive and unified design.

User control is also critical in a user interface design because it gives users the power to decide how they interact with the product or service. Usability experts evaluate the level of user control by looking at the design of the navigation, the placement of buttons and prompts, the feedback given to users, and the ability to undo actions. Again, usability testing plays an important role in heuristic evaluation by allowing researchers to see how users respond to the level of control provided, and gather feedback on any potential hiccups or roadblocks.

Usability Testing and Heuristic Evaluation

Usability testing and heuristic evaluation are both important components of the user-centered design process, and they complement each other in different ways.

Usability testing involves gathering feedback from users as they interact with a digital product. This feedback can provide valuable insights into how users perceive and use the user interface design, identify any usability issues, and help validate design decisions. Usability testing can be conducted in different forms, such as moderated or unmoderated, remote or in-person, and task-based or exploratory. Check out our usability testing 101 article to learn more.

On the other hand, heuristic evaluation is a method in which usability experts evaluate a product against a set of usability principles. While heuristic evaluation is a useful method to quickly identify usability issues and areas for improvement, it does not involve direct feedback from users.

Usability testing can be used to validate heuristic evaluation findings by providing evidence of how users interact with the product or service. For example, if a usability expert identifies a potential usability issue related to the navigation of a website during heuristic evaluation, usability testing can be used to see if users actually have difficulty finding what they need on the website. In this way, usability testing provides a reality check to the heuristic evaluation and helps ensure that the findings are grounded in actual user behavior.

Usability testing and heuristic evaluation work together in the design process by informing and validating each other. For example, a designer may conduct heuristic evaluation to identify potential usability issues and then use the insights gained to design a new iteration of the product or service. The designer can then use usability testing to validate that the new design has successfully addressed the identified usability issues and improved the user experience. This iterative process of designing, testing, and refining based on feedback from both heuristic evaluation and usability testing leads to a user-centered design that is more likely to meet user needs and expectations.

Conclusion

Heuristic evaluation is a powerful usability research technique that usability experts use to evaluate digital product interfaces based on a set of established principles of user experience design. After all these years, the ten principles of heuristic evaluation still cover the key areas of design that impact user experience, making it easier to identify usability issues early in the design process, leading to faster and more efficient design iterations. Usability experts play a critical role in the heuristic evaluation process by identifying design flaws and areas for improvement, using user testing to validate design decisions, and ensuring that the product is optimized for its intended users.

Minimalist design and user control are two key principles that usability experts focus on during the heuristic evaluation process. A minimalist design is clean, simple, and focuses on the essentials, while user control gives users the freedom and control to undo/redo actions and exit out of situations if needed. By following these principles, usability experts can create an exceptional design that enhances visibility, reduces cognitive load, and provides a positive user experience. 

Ultimately, heuristic evaluation is a cost-effective way to identify usability issues at any point in the design process, leading to faster and more efficient design iterations, and improving user satisfaction and retention. How many of the ten heuristic design principles does your digital product satisfy? 

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What do you prioritize when doing qualitative research?

Qualitative user research is about exploration. Exploration is about the journey, not only the destination (or outcome). Gaining information and insights about your users through interviews, usability testing, contextual, observations and diary entries. Using these qualitative research methods to not only answer your direct queries, but to uncover and unravel your users ‘why’.

It can be important to use qualitative research to really dig deep, get to know your users and get inside their heads, and their reasons. Creating intuitive and engaging products that deliver the best user experience. 

What is qualitative research? 🔎

The term ‘qualitative’ refers to things that cannot be measured numerically and qualitative user research is no exception. Qualitative research is primarily an exploratory research method that is typically done early in the design process and is useful for uncovering insights into people’s thoughts, opinions, and motivations. It allows us to gain a deeper understanding of problems and provides answers to questions we didn’t know we needed to ask. 

Qualitative research could be considered the ‘why’. Where quantitative user research uncovers the how or the what users want. Qualitative user research will uncover why they make decisions (and possibly much more).

Priorities ⚡⚡⚡⚡

When undertaking user research it is great to do a mix of quantitative and qualitative research. Which will round out the numbers with human driven insights.

Quantitative user research methods, such as card sorting or tree testing, will answer the ‘what’ your users want, and provide data to support this. These insights are number driven and are based on testing direct interaction with your product. This is super valuable to report to stakeholders. Hard data is difficult to argue what changes need to be made to how your information architecture (IA) is ordered, sorted or designed. To find out more about the quantitative research options, take a read.

Qualitative user research, on the other hand, may uncover a deeper understanding of ‘why’ your users want the IA ordered, sorted or designed a certain way.  The devil is in the detail afterall and great user insights are discoverable. 

Priorities for your qualitative research needs to be less about the numbers, and more on discovering your users ‘why’. Observing, listening, questioning and looking at reasons for users decisions will provide valuable insights for product design and ultimately improve user experience.

Usability Testing - this research method is used to evaluate how easy and intuitive a product is to use.  Observing, noting and watching the participant complete tasks without interference or questions can uncover a lot of insights that data alone can’t give. This method can be done in a couple of ways, moderated or unmoderated. While it can be quicker to do unmoderated and easier to arrange, the deep insights will come out of moderated testing. 

Observational - with this qualitative research method your insights will be uncovered from observing and noting what the participant is doing, paying particular attention to their non-verbal communication. Where do they demonstrate frustration, or turn away from the task, or change their approach? Factual note taking, meaning there shouldn’t be any opinions attached to what is being observed, is important to keep the insights unbiased.

Contextual - paying attention to the context in which the interview or testing is done is important. Is it hot, loud, cold or is the screen of their laptop covered in post-its that make it difficult to see? Or do they struggle with navigating using the laptop tracker? All of this noted, in a factual manner, without personal inferring or added opinion based observations can give a window into why the participant struggled or was frustrated at any point.

These research methods can be done as purely observational research (you don’t interview or converse with your participant) and noting how they interact (more interested in the process than the outcome of their product interaction). Or, these qualitative research methods can be coupled with an

Interview - a series of questions asked around a particular task or product. Careful note taking around what the participant says as well as noting any observations. This method should allow a conversation to flow. Whilst the interviewer should be prepared with a list of questions around their topic, remain flexible enough to dig deeper where there might be details or insights of interest. An interviewer that is comfortable in getting to know their participants unpicks reservations and allows a flow of conversation, and generates amazing insights.

With an interview it can be of use to have a second person in the room to act as the note taker. This can free up the interviewer to engage with the participant and unpick the insights.

Using a great note taking side kick, like our Reframer, can take the pain out of recording all these juicy and deep insights. Time-stamping, audio or video recordings and notes all stored in one place. Easily accessed by the team, reviewed, reports generated and stored for later.

Let’s consider 🤔

You’re creating a new app to support your gym and it’s website. You’re looking to generate personal training bookings, allow members to book classes or have updates and personalise communication for your members. But before investing in final development it needs to be tested. How do your users interact with it? Why would they want to? Does it behave in a way that improves the user experience? Or does it simply not deliver? But why?

First off, using quantitative research like Chalkmark would show how the interface is working. Where are users clicking, where do they go after that. Is it simple to use? You now have direct data that supports your questions, or possibly suggests a change of design to support quicker task completion, or further engagement.

While all of this is great data for the design, does it dig deep enough to really get an understanding of why your users are frustrated? Do they find what they need quickly? Or get completely lost? Finding out these insights and improving on them can make the most of your users’ experience.

When quantitative research is coupled with robust qualitative research that prioritizes an in-depth understanding of what your users need, ultimately the app can make the most of your users’ experience.

Using moderated usability testing for your gym app, observations can be made about how the participant interacts with the interface. Where do they struggle, get lost, or where do they complete a task quickly and simply. This type of research enhances the quantitative data and gives insight into where and why the app is or isn't performing.

Then interviewing participants about why they make decisions on the app, how they use it and why they would use it. These focussed questions, with some free flow conversation will round out your research. Giving valuable insights that can be reviewed, analyzed and reported to the product team and key stakeholders. Focussing the outcome, and designing a product that delivers on not just what users need, but in-depth understand of why. 

Wrap Up 🥙

Quantitative and qualitative user research do work hand in hand, each offering a side to the same coin. Hard number driven data with quantitative user research will deliver the what needs to be addressed. With focussed quantitative research it is possible to really get a handle on why your users interact with your product in a certain way, and how. 

The Optimal Workshop platform has all the tools, research methods and even the note taking tools you need to get started with your user research, now, not next week! See you soon.

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