What’s The Adequate Number Of Interviews For A Grounded Theory Approach?

Researchers need to stop thinking of sample size as a rigid set of rules and instead think of it as a useful tool in the research process. Moreover, they should stop using the word “adequate” when talking about sample size because adequate is too absolute to be helpful. 

Instead, researchers should use sample size as a means with which to inform research decisions. 

Finally, since qualitative studies do not have standard procedures for determining an appropriate sample size, researchers are more flexible with their data analysis and conclusion stages than quantitative studies.

When to Stop Gathering Qualitative Data – YouTube
Key Takeaways
– Determining the appropriate number of interviews is a crucial consideration in grounded theory research.
– The adequate number of interviews varies based on factors such as research goals, complexity of the topic, and data saturation.
– Data saturation, where new interviews yield minimal new information, is a key indicator to stop conducting interviews.
– Quality of insights from interview participants is more important than a high quantity of interviews.
– Combining qualitative and quantitative approaches can inform decisions about interview sample sizes.

Qualitative Methods Are Not Scrutinized As Much As Quantitative Methods

In the field of social science research, there is a consensus that qualitative methods are not scrutinized as much as quantitative methods. The research community is less strict about the number of interviews needed for a grounded theory approach. 

This is because the goal of grounded theory is to generate new concepts and categories from your data, rather than test existing ones.

The example below shows how you can use 1 interview to create new concepts:

Describe your current home situation in one sentence (e.g., “I live with my boyfriend.”)

Ask yourself why this situation is taking place? Why do you live with him/her? What do you see as good about this living arrangement? What do you hate about it? Consider exploring how your current living situation might change over time if certain events occur (e.g., marriage).

When conducting qualitative research, understanding the art of crafting questions is crucial. Learn more about the art of effective questioning in our guide on asking questions about everyday lives, which can significantly enhance your interview outcomes.

Why Do We Need A Sample Size?

The sample size is an important component of grounded theory. It’s not a limitation, but rather a decision-making tool that helps researchers make informed decisions about how to proceed with their study. 

As such, you must understand what your sample size is and how it will help you as you conduct your grounded theory work.

It’s important to note that grounded theory is a qualitative method; it doesn’t use quantitative measures like the number of interviews or surveys conducted within a certain time frame or geographic location. 

Instead, grounded theorists rely on inductive reasoning the process of using data to create theories to generate new ideas about human behavior over time (Strauss & Corbin 1990).

A Common Flaw Of GT Studies

When conducting grounded theory, you want to make sure that your sample size is neither too large nor too small. If you have too few participants, then it’s difficult to get a holistic view of the phenomenon in question. 

If you have too many participants and take that data into account during coding, chances are good that your analysis will be faulty or at least misleading.

In addition to making sure that your sample size is appropriate for GT studies, it’s important to remember that the samples themselves should be as diverse as possible when looking at different types of audiences (or even individuals). 

In other words: if both men and women are included in your study population but they’re all white or middle class or able-bodied that can skew the results!

So What Is An Adequate Sample Size?

So, how do you know if your sample size is adequate? The size of your sample depends on the research question and how much information you want to get from each interview. 

If you are trying to understand the meaning of something that people experience in their daily lives, then it might be enough to interview a small number of people (10-12 participants). 

But if you want a more scientific understanding of social phenomena or behavior across a large population, then it might take hundreds or even thousands of participants for an adequate sample size.

Of course, it’s also possible that neither one is true about your research questions! Maybe there are many ways in which people experience these things differently, so some participants would have less meaningful perspectives than others. 

Or maybe there isn’t just one way that people behave around these things; rather there are multiple types who will provide different kinds of information about social life overall. 

In either case, it’s best not to assume that there is one right answer here or even any one best way at all

Research is a blend of observation, inference, and rigorous testing. Dive into the scientific approach with insights from observation, inference, and testing to enrich your understanding of research methodologies.

What Can Researchers Do?

In studying grounded theory, there is a debate about how many interviews you need before you begin coding your data. Some researchers have said that if you have 35 interviews, then it’s okay to begin coding your data. 

Others say that you should have 200 or more interviews before beginning to code. In the end, however, it comes down to what research questions you’re trying to answer and how much time and money the project has available.

You’ll want to look at your research questions and decide how many interviews would be needed based on those questions (that is, “how many people do I need?”). 

Then consider what resources are available for conducting these interviews (time and money) so that your sample size will fit within those constraints without compromising the quality of research findings too much (i.e., don’t set a predetermined number of cases!).

If this sounds like too much math for your taste and let’s face it: most of us feel like we know when something feels right.

Then consider using a literature review as an input into defining sample size as well as designing appropriate sampling methods for gathering data from different types of populations (e.g., telephone surveys vs internet surveys).

Stop Using The Word “Sufficient” Sample Size

The term “sufficient sample size” should be retired. The word sufficient implies that research is finished once a certain number of interviews has been conducted, and this goes against everything grounded theory does. 

A grounded theorist will always strive to get more data because she knows that there’s always more that can be discovered about the topic under study.

The goal of grounded theory research isn’t to obtain a sufficient sample size but rather to use your data in ways that help you make decisions about your research question and its relationships with other variables. 

The sample size is just one tool among many others used to guide these decisions (e.g., looking at patterns in the data; using triangulation methods).

Use Sample Size As A Tool For Research Decisions, Not Limitations

It may be tempting to think that the bigger your sample size is, the more reliable and trustworthy your data will be. However, this isn’t always true. Many other factors determine how good your research is.

For example: if you use an inductive approach but don’t include enough interviews from different perspectives (e.g., male vs female).

Then you might get a skewed view of what people think and feel about something important like marriage or childcare responsibilities which in turn might affect how you design policies around these issues!

So while it’s still important to make sure that your project has enough participants involved so that their voices are heard properly… remember also that there’s no such thing as “too much” when it comes to finding out new things about ourselves and others around us!

Selecting the right participants is a cornerstone of effective research. Learn how to pinpoint the perfect candidates for your research panel in our article on identifying the right people for a successful research endeavor.

Use Your Data To Define Sample Size

First, you should determine the sample size based on the data that you have. You may have enough information to define a sample. For example, if you are doing grounded theory and have lots of documents.

Then maybe it makes sense for you not to interview any more people as long as they can help explain your theory better. 

However, if you don’t have very many documents or cases yet, then interviewing more people might be needed so that they can provide additional relevant information.

Second, use these guidelines:

The number of participants should be half the total number of cases (or data points). This is called “the rule of the half.”

Your goal is always to collect all available data rather than just some random samples from a population so that everyone has an equal chance of being included in your study without bias affecting their inclusion (or non-inclusion).

Don’t Set A Predetermined Number Of Interviews Or Cases

As you can see, this is a substantial amount of work for one person to undertake. It is also very time-consuming. 

You may be tempted to set a predetermined number of interviews or cases for your study (e.g., 8). This is not recommended because it will make it difficult for you to know when you have reached saturation and whether or not any additional data are useful.

How do we know if we are done? A general rule of thumb is that when the same ideas appear repeatedly across multiple cases, then there could be some validity in analyzing those themes together as part of a bigger idea or pattern in your research question.

Get Input From Literature Review

It is important to get ideas from the literature review. For example, if you are studying something like bullying in the workplace and you want to know what causes it, what kind of behavior contributes to it,

And how people react when they are bullied, then you can use literature that has already been written on the subject. 

You can also use literature reviews as a way of getting input about your research problem and your research questions. 

In addition, if there is any way that your study could be improved upon by previous studies or those who have done similar work before you then it would be useful for you to look at their methods section to see if there are any issues that need changing with yours.

How Many Interviews Are Enough Before You Begin Coding Your Data?

You can’t say how many interviews are enough until you know what you’re looking for.

To determine what your data needs to tell you, start with the research question (e.g., “What are the most important reasons why people choose one brand over another?”). Then, design the study around that goal. 

For example, if your goal is to identify some of the most common reasons why people choose one brand over another, 

Then it makes sense that more interviews would be required than if your goal was simply to find out whether brands have different meanings depending on who buys them.

The next step is determining how many interviewees will provide enough data for you based on a grounded theory approach and its internal validity criteria (see previous blogs). 

You’ll want enough cases so that each episode has been represented at least once within each category being studied and ideally twice or more times (e.g., two individuals who both buy Brand A but do so for different reasons would be ideal candidates). 

This helps ensure that any patterns found in categories reflect actual differences between groups rather than just random anomalies in individual behavior; 

It also helps ensure that all parts of an episode’s content are represented somewhere in those categories’ analysis categories.[1]

Marketing research requires innovative strategies that can draw parallels from unexpected places. Explore insights from the ultimate guide to Super Bowl marketing research to find new perspectives on advanced research techniques.

How Many Interviews Are Enough Before You Begin Writing The First Draft?

You have to have enough data before you write the first draft. We don’t do any writing until we have at least 50 interviews, and I would probably say that’s a good number for most people to start with.

We’ve never written a paper without reading everything. We’ve always read every single interview from beginning to end before we write anything.

Because if there are things that don’t make sense or need more explanation, then those are the kinds of things you want them to find out in their discovery process while they’re writing it.

Research Is Fluid And Dynamic; Rigid Rules Will Hinder The Research Journey

As you progress through your research, keep in mind that the interview questions and procedures may need to be modified. 

You may find that the data you gather is not useful or relevant to your research questions, or you may find yourself struggling with how best to present this data. For example:

Your first few interviews might take place on a weekday and then move into weekends as your schedule allows.

You might end up interviewing people individually instead of in groups because there are fewer participants available during some times of day, or because they’re less comfortable sharing their experiences with others.

You may decide that it would be beneficial for all data collection sessions (e.g., focus groups) to take place at one location so that participants can meet each other before starting their interviews with you (this also reduces travel time).

Conducting focused and powerful interviews is a skill that can elevate your research outcomes. Discover the secrets of running rocket-powered, hyper-focused interviews to glean invaluable insights from your participants.


You will never be able to fully predict how many interviews you need until you have collected and analyzed a number of them. 

Unfortunately, this can become a major barrier for researchers who are inexperienced with qualitative methods because it requires a great deal of confidence in their research abilities. 

We encourage researchers to trust the process more and think about sample size as an ongoing process that changes from step to step.

Further Reading

Explore these additional resources to deepen your understanding of qualitative research and interview methodologies:

Exploring the Dynamics of Qualitative Research: This article delves into the intricate dynamics that underlie qualitative research, shedding light on the nuances of participant interaction and data analysis.

Optimizing Interview Sample Sizes in Qualitative Research: Discover strategies for determining the optimal sample sizes for qualitative interviews, ensuring data richness and saturation.

Determining the Adequate Number of Interviews: Explore insights from researchers discussing the challenges and considerations involved in deciding the appropriate number of interviews for qualitative studies.


What factors influence the number of interviews in qualitative research?

The number of interviews can be influenced by various factors, including the research scope, desired data saturation, and the complexity of the research topic.

Is there a fixed rule for determining the number of interviews in qualitative research?

There isn’t a one-size-fits-all rule. The number of interviews often depends on the research goals and the point at which data saturation is achieved.

How can I ensure data saturation in my qualitative research?

Data saturation occurs when new interviews yield little to no new information. Conducting interviews until this point is reached ensures comprehensive data coverage.

Should I prioritize quality over quantity when selecting interview participants?

Absolutely. The quality of participants and the richness of their insights matter more than the sheer number of interviews conducted.

Can I combine qualitative and quantitative approaches when determining interview numbers?

Yes, employing a mixed-methods approach can provide a more comprehensive perspective. Quantitative data might inform decisions about qualitative interview sample sizes.