03 · What You Need to Know
Move from question to evidence before moving from question to methods
A research question tells you what you want to know. It does not automatically tell you how to find out.
The bridge between those two points is a series of linked decisions. You need to determine what an acceptable answer would require you to observe, compare, measure, interpret, estimate, describe, or explain. From there, you can identify the appropriate sources of evidence and choose a design capable of connecting that evidence to the question.
This sequence matters because the research question should drive the design rather than being retrofitted to whatever method happens to be familiar. Methodological literature consistently treats the research question as foundational to study design, while feasibility includes practical considerations such as access to participants, expertise, resources, and time.
First ask: What would I need to know to answer this question?
Before naming a methodology, imagine that the study has been completed successfully. What evidence would allow you to answer the research question?
Suppose your question is:
How do first-year university students experience the transition from fully online learning to face-to-face classes?
An answer requires evidence about students' experiences, interpretations, challenges, and perhaps how those experiences vary. Simply obtaining their examination scores would not directly answer that question.
Now consider a different question:
Is participation in a supplemental mathematics tutorial associated with first-year students' final mathematics grades?
Here, detailed accounts of students' experiences might be interesting, but they would not by themselves provide the evidence needed to estimate the stated association. You would need information about tutorial participation and mathematics outcomes, together with whatever additional variables and design considerations are necessary for a defensible analysis.
The wording of the question therefore begins to constrain what counts as relevant evidence. WHO guidance similarly emphasizes that a clear research question helps determine study design, sampling, and analysis, while outcomes should be chosen so that the study can actually answer the question.
Identify the unit or source of evidence
Once you know what evidence is required, ask where it could come from.
Depending on the research question, the relevant source might be people, classrooms, organizations, documents, published studies, administrative records, social media posts, biological specimens, images, transactions, experiments, sensors, archival materials, or an existing dataset.
This decision sounds obvious, but it can substantially reshape a study. Consider the question:
How consistently do universities disclose their policies on generative AI?
If the object of interest is the content of official institutional policies, students may not be the primary source of evidence at all. The relevant units could instead be university policy documents or official webpages.
Clarifying the unit of analysis and evidence source early helps prevent a common methodological mismatch: collecting data from an accessible source simply because it is accessible, rather than because it can answer the question.
Determine the broad design that can produce the evidence
Only after clarifying the required evidence should you ask what broad research design could produce it credibly.
This does not mean you must immediately specify every procedure. At this stage, you may only need to determine whether the question points toward an experiment, observational study, survey, qualitative inquiry, case study, secondary-data analysis, systematic review, mixed-methods design, or another appropriate approach.
There is no universally superior design independent of the question. A design is appropriate insofar as it can generate evidence suited to the claim you intend to make. Research-methods literature consequently emphasizes that design selection should follow from the research question rather than from a generic hierarchy of supposedly superior methods.
| If your question primarily asks... |
You need evidence about... |
A broad design might involve... |
| What is happening or how common is it? |
Characteristics, distributions, frequencies, or patterns |
Descriptive surveys, observational data, records, or other descriptive designs |
| Are two or more phenomena related? |
Variables or characteristics that can be examined together |
Correlational or other observational designs |
| Does an intervention produce a difference? |
Outcomes under appropriately compared conditions |
Experimental or quasi-experimental designs where appropriate |
| How do people experience or understand something? |
Accounts, meanings, perceptions, practices, or interpretations |
Qualitative interviews, focus groups, observations, documents, or related approaches |
| How does a phenomenon unfold in context? |
Processes, interactions, circumstances, and contextual evidence |
Case study, ethnographic, longitudinal, qualitative, or mixed approaches depending on the question |
| What does the existing research collectively show? |
Eligible existing studies and their findings |
Systematic or other appropriately designed evidence synthesis |
These are orientations, not automatic conversions. Two similarly worded questions may require different designs because of the claims being made, the available evidence, disciplinary conventions, or practical constraints.
Clarify the population, setting, cases, or material of interest
The next decision is not necessarily the exact sample size. It is usually the broader question of what or whom the study is about.
If you are studying people, distinguish the population of substantive interest from the participants you happen to be able to recruit. If you are studying institutions, define what counts as an eligible institution. If you are analyzing documents, determine what kind of documents fall within the scope. If you are conducting secondary-data research, identify the records or dataset capable of representing the relevant population or phenomenon.
For some quantitative questions, structured frameworks make these elements explicit. In clinical and health research, for example, PICO and related formulations can help specify population, intervention or exposure, comparison, and outcome. Such frameworks are useful where they fit the question, but they should not be forced onto research traditions for which they were not designed.
Identify the central concepts, variables, outcomes, or phenomena
A question may sound clear in ordinary language while remaining ambiguous methodologically.
Consider:
Does social media use affect academic performance among university students?
What counts as social media use? Total screen time? Time on particular platforms? Academic versus recreational use? Self-reported use or device-recorded behavior?
What counts as academic performance? Grade point average? Course grades? A standardized assessment? Student perceptions of their performance?
You do not necessarily need to finalize every operational definition immediately, but you should identify the concepts that will eventually require definition or measurement. Otherwise, you may discover later that different parts of the project have been using the same words to mean different things.
This is especially consequential when a study has a primary outcome. WHO guidance on research questions recommends careful advance consideration of outcomes so that the resulting evidence can answer the intended question.
Check what is already known before locking in the design
A settled research question should still be tested against the literature.
The literature may reveal that the question has already been answered convincingly, that an important variable has been overlooked, that a proposed measure performs poorly, or that previous researchers repeatedly encountered the same recruitment problem. It can also reveal established designs, instruments, datasets, theoretical perspectives, and methodological disagreements relevant to your choices.
This does not mean copying the most common design. Prior studies are evidence about how the problem has been approached, not instructions that must be followed.
The review may even require you to revise the question. Research planning is iterative. A question can be sufficiently settled to guide planning without being protected from evidence that exposes a serious problem.
Test the emerging design against feasibility
An appropriate design is not automatically a feasible design.
Feasibility includes whether you can obtain enough relevant participants or cases, access the required setting or dataset, use the necessary equipment or software, complete the work within the available time, meet the financial costs, and obtain the methodological or technical expertise the study requires. These considerations are widely recognized as part of assessing whether a research question can become a viable study.
This creates an important feedback loop:
Research question What exactly are you trying to find out?
Required evidence What observations, measurements, comparisons, accounts, or materials could answer it?
Broad design What study structure could produce or obtain that evidence credibly?
Feasibility check Can that design actually be conducted with your access, resources, expertise, ethics requirements, and time?
Refinement If not, revise the design, scope, or question without sacrificing the scientific purpose that made the study worthwhile.
Feasibility work can itself be empirical. In some settings, pilot or feasibility studies are used to test recruitment, retention, intervention delivery, measurement, or other procedures before a larger study is undertaken.
Consider ethics while the design is taking shape
Ethics should not be treated as a final checkpoint after all methodological choices have been made.
The population, recruitment method, data collected, intervention, consent process, privacy protections, incentives, risks, and data-sharing arrangements may all have ethical implications. A design that cannot be conducted ethically is not an acceptable design simply because it answers the question efficiently.
At this stage, you may not yet have all the documentation required for formal review. You should, however, be able to recognize whether your emerging choices raise ethical or regulatory issues that could materially affect the study.
Do not confuse the broad design with the complete protocol
Knowing that you will conduct a qualitative interview study does not yet tell you the sampling strategy, recruitment procedure, interview guide, recording arrangements, analytic approach, data-security procedures, or stopping logic.
Likewise, deciding on an observational quantitative study does not settle the exact variables, measurement procedures, sample-size considerations, missing-data strategy, statistical model, or quality-control procedures.
Those decisions matter, but they are downstream of the basic question-to-evidence logic. A research protocol eventually makes many of these choices explicit. WHO's recommended protocol structure, for example, asks researchers to specify objectives, study design, population, sampling, data collection, analysis, ethical considerations, and other operational details.
The useful distinction is between knowing what kind of study you are building and having every construction detail finalized. The latter develops progressively as you determine how detailed the research plan needs to be before you begin.
The decisions are sequential, but not perfectly linear
It would be convenient if research planning worked as a one-way sequence in which the question permanently determines the design, the design determines the sample, and everything thereafter simply follows. In practice, researchers move back and forth.
You may discover that the desired population cannot be accessed. A validated instrument may not exist in the necessary language. A dataset may lack a crucial variable. A preliminary sample-size assessment may show that the intended comparison is unrealistic. An ethics issue may make a proposed procedure inappropriate.
When that happens, revisiting an earlier decision is not necessarily a planning failure. It is often precisely what planning is for.
Watch Out
Do not preserve the wording of a research question at all costs while quietly changing the population, evidence, outcomes, or design until the study no longer answers it. If feasibility forces a substantial methodological change, return to the question and check whether the revised study can still support the claim you originally intended to make.