How Many Groups? The Truth About Market Research Focus Groups

By David M. Schneer, Ph.D./CEO

5-Minute Read

I recently wrote a blog regarding a frequently asked question: how many interviews do we need to do? The real answer is, “it depends.” But, as we previously mentioned, our clients can’t conduct research with “it depends”.

The Pandemic tore a path through the research norms that companies came to rely on over the years. Everything changed as a result and companies are scrambling to keep up with the changing needs and behaviors of their customers. Qualitative research is designed for just this purpose—depth of understanding.

But what about focus groups? Well, it depends too, but here are some guidelines based on our experience and the corpus of literature scanned on the topic.

The Complexity of Focus Groups

Let’s make sure we’re all singing from the same song sheet and define a focus group. It has, in my opinion, been one of the most misunderstood and misused methodologies. We’ll use Davidson’s classic (1975) definition: “A focused group interview is a qualitative tool for collecting information in which a number of respondents simultaneously discuss a given topic under the guidance of a moderator.”[1]

Before we dive into the number of groups, we need to discuss the complexion of this methodology. For example, the variables that need to be considered when conducting groups include, but are not limited to:

  1. The objectives: what does the client want to learn, specifically?
  2. The size of the group (i.e., how many individuals per group)
  3.  The time of the groups: although many groups are held during the evening, some can be held during the morning or lunch.
  4.  The day: Mondays and Fridays are often not good days to conduct research, although this is not always the case.
  5. The location: where should the groups be held? In which cities?
  6. The duration: how long should the groups last? 60 minutes? 90? 120?
  7. Virtual versus in-person: the rule of thumb here is if the cost of a new product introduction is great, best to conduct these groups in-person where respondents can physically interact with the device, for example. Virtual can be used for all else.
  8. The composition of the group participants: are the groups homogenous, that is are they all of the same demographic?
  9. Client budget: this often dictates the approach.
  10. Timing and, of course,
  11. The moderator: is the moderator experienced in the subject matter?

And then there are different focus group use cases. For example, the focus groups used for a doctoral study are different from those used in psychotherapy focus groups or focus groups used for business exploration. Regarding this blog, we’ll focus on groups used in business.

Once you factor in the abovementioned variables, then the question becomes, do you need focus groups at all?  In other words, in a qualitative study, is it better to conduct focus groups or in-depth interviews?

Focus Groups or In-depth Interviews?

A simple way to assess whether to use focus groups or in-depth interviews hinges on their purpose. If you want to have people privately evaluate a new product concept or some other stimulus, in-depth interviews are recommended. Why? Because you want to mitigate groupthink—that is when people gather in a group, they tend to bias one another. On the other hand, if you are trying to generate new ideas and product use cases, focus groups are ideal for this purpose. The group dynamic can often spark new ideas that would never have flared up in an in-depth interview.

How Many Groups?

Now that we have defined a focus group and discussed the variables that comprise them as well as decision to conduct them or not, we can now move on to the number of groups needed. And is there such a thing as Theoretical Data Saturation (TDS) in groups as we have observed with in-depth interviews? The short answer is yes.

A lot can be accomplished with smaller number of groups. In some cases, anywhere from two to four groups can be used for exploratory research.

As we saw in our expose of in-depth interviews, the key to determining the optimal number of focus groups hinges again on homogeneity. Let’s use a simple and fun example.

Cats and Dogs

Let’s assume the client makes pet food. Their first target audience is dogs. The client would like to get a group of dogs together to generate new flavor ideas for their food. The question becomes how many dog groups do we need to do? The client could do one group of dogs, but that could be dangerous. Without conducting another group of similar dogs, you never know if the one group you conducted is atypical, or not. So, in general, we recommend conducting at least two groups of dogs.

That’s fine if you want to conduct groups of dogs in the San Francisco Bay Area. But what about dogs in New York City? Are they any different? Sure, they are. Those New York dogs have a lot of attitude. Okay, so you conduct two dog groups in New York. That’s four. Add another city, and that’s six. And so on.

But wait! Are all dogs the same? Do you need to stratify them by size, weight, age, or breed? Pretty soon you got a lot of input from a lot of dogs. That’s expensive, time-consuming, and likely messy.

However, Theoretical Data Saturation could kick in. We’ve seen Theoretical Data Saturation in as few as six groups and more likely between eight and twelve. That is, once you talk to six plus dogs you begin to hear the same thing: eat, sniff, pee, bark, walk, sleep, eat, sniff, etc.

But now the client says they want to market to cats. As many a cat owner will tell you, cats are different. They tend to do what they want. So, mixing cats and dogs in a focus group would be chaotic. Now you want to conduct two groups of cats and two groups of dogs in each market. As you can see, the homogeneity of this can drive up the number of groups and it can drive up costs and timing quickly. And if you mix cats and dogs in a group, the fur will fly.

In this instance, there are several fixes. You can prioritize your target audience, have smaller groups, consider virtual versus in-person which can be more expensive.

The number of focus groups a company needs is a tricky question involving lots of variables and discussion. An experienced Market Research firm will be able to guide a potential client into making the best decision to fit its budget and project requirements. Every research project is different and unfortunately there is no one size fits all answer. Instead, it takes years of trial and error to understand the nuances of a market research project and to know how best to lead it.

The one thing you can be sure of is experience matters and that is what a company needs to look for in the market research firm with which it ends up working.

If you have a need for focus groups, let our decades of experience help you determine the right number.

[1] What Influences Saturation Estimating Sample Sizes in Focus Group Research, Monique Hennink, Bonnie N. Kaiser, and Mary Beth Weber, Qualitative Health Research, 2019, vol. 29 vol 10, pps. {1483 – 1496},