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Factors to determine your sample size for qualitative research

Rachel Davies 11/4/21 10:30 AM
Factors to determine your sample size for qualitative research

A common question that is asked when working with new and existing clients is sample size - it always crops up along with further enquiries around minimum sample size, what constitutes a large sample and should I be aiming to get more people for quantitative research purposes?

The health of your qualitative research, as always, will depend on what it is you are aiming to discover - There are many elements that affect research and in this blog, we will look at some key factors that you can implement into your sample size when executing qualitative research.

Factors that determine your sample for qualitative research project can have a huge impact on your findings

It's a journey

Sample size for qualitative research is an organic process.

From the outset defining your sample size will be the first hurdle to jump through, but in these early stages, we need to acknowledge that who you initially acquire may not be your final selection of people. Often, when building a sample size in qualitative research, a good place to start is with a quantitative method such as a survey or questionnaire. From here you can segment your audience into a population that you are targeting or hoping to attract.

For example, if you were an academic institution such as a university, and you were wanting insight on how to improve your student services, you would first weigh up what would be an adequate sample size and what you were hoping to discover. An approach you may want to take is to canvas a large number of learners via a quantitative survey to their student accounts, and segment the responses into a smaller, 30-50 student group that best represents the audience you want to reach. Within that new group, you can launch a qualitative research campaign that is representative of your education institution.


Planning the journey of your qualitative research.

1. Have different research methods for different stages of your research journey.

2. Be open to new methods of collecting data and information.

3. Break up your larger sample into smaller groups depending on how they answer or score in preliminary research activities.


Determining sample sizes in qualitative research does matter;

(but bigger isn't always better)

Modern technology and AI is changing the way in which we manage research methods. The advancements that are happening mean you are able to process a large set of data. When determining sample size we need to step back from our traditional understanding of what we perceive qualitative research to be and consider what is the question we need answering and what sample do we have readily available?

Focus groups, in-depth interviews and consultations can produce great sample data and a range of info for you and your team to have a discussion; but ensuring the people you are sampling are relevant and appropriate is half the battle. Often we discover that the more you research and understand what you are wanting to discover, your sample size will become clear.

Experience tells us that sample sizes depend on the campaign you are deploying so you should consider one of the following methods.

    1. Start large and reduce.
      Quantitative research is a great way to recruit a large sample of people which can then be reduced and introduced to qualitative methodologies. This approach enables you to handpick a population of individuals that match your criteria or target audience - aim to lower the initial sample size down to around 30-40 participants.

    2. Communities.
      These can accommodate large numbers of participants - often around 200, and using platforms that are designed in a WhatsApp style, can provide qualitative data where you can interact with participants using a range of qualitative (and quantitative) tools, guide them onto related points and answer any questions. Campaigns such as these could operate anywhere between 3 and 14 days.

    3. Long-Term Campaigns.
      This form of qualitative research can involve a large sample - sometimes up to 1000 participants and studies can last up to 12 months. Discussion is ongoing with a range of different activities to keep respondents engaged.


In community projects, participants can be contacted for qualitative discussions or interviews


Managing your sample size in qualitative is key

Let's be clear, there is no one size fits all approach when determining sample size; we can however be as scientific as possible with our methodology. When your research calls for larger samples, you'll need to manage that group of participants in a practical and nurturing way. If you are running a long-term community project with a high number of participants, engagement and analysis with your respondents can get expensive; but managing relationships and interactions will yield the best results so how do we achieve this?

Incentivise your project

When launching your project, consider adding an incentive that will motivate your sample to respond regularly and in detail. Look at the range of participants that you are working with and assess what a suitable reward could be.

Communicate in their language on a regular basis

This might seem like an obvious point to make, but depending on your campaign, interaction and engagement with your sample will yield greater results. If a respondent feels like they are being valued and moderators are taking note of their thoughts and responses, you are going to get less saturation with your findings.

Choose a platform that works for you

With a number of research platforms now on the market, it's essential that you choose one that suits the way in which you work and the budget you have available. When making a choice, check that it has the ability to centralise and store depth interviews, quantitative research, links to articles and performs a high level of analysis. If it is unable to do any of this, especially the analysis, then search for a platform that does.

Sample size in qualitative research is about insight

The most important factor for researchers when conducting qualitative research is the quality of insight that you are obtaining. At each stage of planning, you need to be considering what data you are wanting to study and in particular, what you are going to do with it. You do not want your sample to suffer from saturation so it's vital you are asking the correct questions and deploying the right methodology to your campaign.

Why do I write this? Because qualitative research is all about the level of insight you are wanting to harness. As mentioned previously, work with a platform that is able to centralise all the information, but importantly, does it in a way that makes sense - in a way that provides value. Insight is all about providing a relevant narrative to your work - whether it is on an 'in-house' company level, or full national level. Researchers will always tell you that insight is key and that you need to choose the correct means of collecting this in order to answer questions you established at the start.

Insight can take the form of heat maps, an interview, discussion on theoretical viewpoints to name a few and any platform should be delivering live, real-time results. The ability to see a large number of the population of your campaign delivering information as it happens enables you to make decisions more quickly and efficiently.


Budgeting for research

How much will it cost?

There is an age-old assumption that qualitative research is more expensive than quantitative because you are having to spend greater lengths of time analysing the data - the notion being the greater the sample sizes, the more time it takes to understand and interpret the research. Researchers have always taken their time to study a chosen method historically this has been a solid, practical way to establish a focus or action point. But as mentioned at the start, technology advances at a lightning pace which means features are being constantly updated resulting in prices being driven down.

Yes, we would be correct in our understanding that a quick, small study will probably be cheaper - it requires fewer working hours and provides a smaller amount of analysis. Therefore it will provide you with good value and is ideal for projects where

Does a larger sample mean a larger bill?

The answer to this is, well a bit of a variable. Your sample size will inevitably play a part in the overall cost but it depends on what it is you are asking them to do and the level of support required. When conducting research the size of your sample will eat a large chunk of your budget if you are wanting a high volume of video content transcribed and analysed for sentiment. This being said, design a narrative in your project so that your sample size can be reduced as the project develops; this way you can save a range of the more data-intensive elements for when you have whittled down your initial cohort.

In our experience, most companies are passionate about research and want to work with anyone who has respect for the field. But when establishing your research budget, consider how much support you require, the amount of prep work you can do 'in-house' and the type of project you want to deploy.



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