Should You Choose a Qualitative Question Because Recruiting a Quantitative Sample Is Impossible?

If you cannot recruit enough participants, should you simply switch to qualitative research?

You planned a quantitative study, but recruitment is proving unrealistic. Perhaps the target population is small, access is restricted, response rates are poor, or the sample required for the intended analysis exceeds what you can reasonably recruit.

Qualitative research may seem like an obvious escape route. Interview studies often involve fewer participants than large surveys or experiments, so why not change the question and conduct interviews instead?

The problem is that qualitative and quantitative research are not distinguished simply by how many participants they require. They are suited to different kinds of questions, evidence, sampling logic, and analysis. A recruitment problem can justify reconsidering your study, but it does not by itself justify a qualitative research question.

Choose qualitative research for the question, not because the sample is smaller

A qualitative study is not a small-sample quantitative study

The temptation to switch methods often begins with a true observation: many qualitative studies use smaller samples than many quantitative studies. The conclusion researchers sometimes draw from this, however, is misleading.

Qualitative sample sizes are not simply reduced quantitative sample sizes. Quantitative studies may require sample-size calculations based on the design, estimand, expected effect, desired precision, statistical power, and planned analysis. Qualitative sampling is typically justified according to the purpose and methodological logic of the qualitative study. Concepts such as saturation are frequently used, while the concept of information power proposes that the more relevant information a sample provides for the study aim, the fewer participants may be required.

Under an information-power approach, sample adequacy depends on factors including the specificity of the study aim and sample, theoretical grounding, quality of dialogue, and analysis strategy. There is therefore no universal rule that “qualitative means a small sample.”

The first question is what you wanted the quantitative study to establish

Before changing approaches, return to the original question. What type of answer were you seeking?

These questions can complement one another, but they are not interchangeable. If you originally wanted to estimate prevalence, interviewing ten people in depth does not provide a small-scale prevalence estimate. It answers a different kind of question.

A recruitment failure does not transform the original question

Imagine that you want to estimate the prevalence of academic burnout among graduate students at a university. Your planned survey requires substantially more responses than you can obtain.

You could interview a smaller purposively selected group and investigate how graduate students experience and interpret academic burnout. That may be a worthwhile study. But it does not answer the original prevalence question.

The second does not automatically follow from the first. You still need to establish why the qualitative question matters.

Do not assume that qualitative recruitment is automatically easy

Qualitative research can involve fewer participants, but those participants may need to meet carefully chosen criteria and provide information relevant to the study aim. Researchers may use purposive, theoretical, criterion-based, snowball, or other sampling strategies depending on the methodology and purpose.

If your original difficulty is access to the population itself, switching approaches may not solve anything. A hard-to-reach population remains hard to reach whether you need survey responses, interviews, observations, or focus groups.

In some situations, qualitative recruitment may be even more demanding because participation requires substantial time, trust, disclosure, repeated contact, or access to particular experiences.

Sample adequacy in qualitative research needs its own justification

It is also a mistake to choose an arbitrary small number of participants and call it sufficient because the study is qualitative.

Different qualitative methodologies make different demands on sampling and analysis. Saturation is widely invoked, but its meaning and appropriate use vary across methodological traditions. Information power offers another way of thinking about adequacy: a narrow aim, highly specific sample, strong theoretical grounding, high-quality dialogue, and an intensive analytic strategy may permit a smaller sample than a broad exploratory question involving a heterogeneous population.

The number should therefore follow the methodological logic of the redesigned qualitative study. It should not be whatever number remained after quantitative recruitment failed.

Changing to qualitative research can be legitimate when the new question matters

None of this means you must remain committed to an infeasible quantitative study. Research planning is iterative. Discovering that recruitment is unrealistic is useful methodological information.

You may decide that a qualitative question addresses an important dimension of the same broader problem. Perhaps prevalence cannot currently be estimated, but understanding why members of the population are difficult to reach is itself consequential. Perhaps an intervention cannot yet be evaluated at scale, but examining how participants experience its implementation could inform future development.

The key is to justify the qualitative study positively: “This evidence is appropriate for this question.” Avoid justifying it negatively: “I could not recruit enough people for something else.”

Mixed methods does not automatically rescue an under-recruited quantitative study

Another temptation is to retain the inadequate quantitative component, add a few interviews, and describe the project as mixed methods.

Mixed methods research involves the intentional collection and integration of quantitative and qualitative evidence to address research questions in ways that use the contributions of both. Simply placing qualitative data beside an inadequate quantitative dataset does not repair the limitations of the quantitative component.

If both forms of evidence are genuinely required, mixed methods may be appropriate. The design, priority, sequencing, and integration of the components should be planned accordingly. It should not function as methodological first aid for a study whose original sample target was missed.

Consider whether the quantitative study can be made feasible before replacing it

Before changing the question, diagnose why recruitment is failing. Could you extend the recruitment period, add legitimate recruitment sites, establish a multisite collaboration, improve access procedures, reconsider unnecessarily restrictive eligibility criteria, or obtain institutional support?

If the method best suited to the question is currently unavailable, the response should begin with the actual constraint rather than an automatic methodological substitution.

Where the problem is specifically local capacity, investigate whether the study could be supported beyond your current institution. Sometimes the question is feasible at another site or through collaboration even though it is infeasible within your immediate setting.

If the question changes, evaluate it again from the beginning

Suppose you ultimately decide that a qualitative question is more realistic and intellectually useful. Treat that question as a research question in its own right.

Return to the literature. Determine whether the question is relevant and sufficiently focused. Identify the qualitative approach that fits it. Consider access, sampling, data generation, analysis, researcher expertise, ethics, and the likely contribution.

This protects against changing the question so extensively to accommodate an available method that feasibility becomes the only reason the new study exists.

From an impossible survey sample to a different qualitative question

Common misconceptions about switching to qualitative research

Let the revised question justify the revised method

If quantitative recruitment becomes impossible, do not ask first whether qualitative research would be easier. Ask what you still need to know about the underlying research problem.

The broader principle is straightforward: the type of research you conduct should follow the kind of evidence needed. Feasibility matters, but it should work alongside that logic rather than replace it.

Before switching from a quantitative to a qualitative question, check this

Questions about choosing qualitative research when recruitment is difficult

A smaller sample is not a methodological justification

How to Cite This Guide

This guide is intended to be read, shared, and used in research, teaching, and academic work. If you draw on its ideas, explanations, or other content, please acknowledge the source by citing the guide. Doing so gives appropriate credit and helps your readers locate the original resource.