03 · What You Need to Know
Study design should be a response to the research question
A study design is not simply a format into which a research topic is inserted.
It establishes how the study will generate or obtain evidence capable of addressing the research question. That means meaningful design decisions require some prior clarity about what needs to be known.
Consider the topic:
Generative AI and student learning.
That topic could support very different questions:
- How frequently do students use generative AI for academic tasks?
- What factors are associated with students' use of generative AI?
- Does access to generative AI affect performance on a particular learning task?
- How do students decide when using generative AI is academically acceptable?
- How does students' use of generative AI change across a semester?
These questions do not merely require different instruments. They require different forms of evidence and potentially different designs.
If you choose “survey research” before deciding which of these questions you are asking, the method begins determining the question rather than the other way around.
The idea should have become a researchable question, not merely an interesting topic
A broad topic is useful during exploration because it allows you to learn the territory.
Study design requires more constraint.
You should be able to state what the project is trying to find out in a form specific enough to identify relevant evidence.
Topic
Academic integrity and generative AI.
Researchable direction
How university students interpret the boundary between acceptable and unacceptable generative AI assistance in assessed coursework.
The second formulation does not yet determine the complete methodology. It does, however, narrow the phenomenon sufficiently that methodological reasoning can begin.
If your question still changes fundamentally whenever you encounter a new article, the idea may need more conceptual development before detailed study design.
You should understand why the question is worth answering
A technically researchable question is not automatically a worthwhile project.
Before investing in detailed design, you should have a reasonable account of why the question matters.
The contribution might involve:
- addressing an important empirical uncertainty;
- examining a phenomenon in a context where evidence is limited;
- testing or extending a theoretical explanation;
- resolving conflicting findings;
- investigating an emerging practice or problem;
- evaluating an intervention, policy, or process; or
- providing evidence needed for a practical decision.
This does not require claiming that nobody has ever studied anything similar. Novelty is rarely that simple.
You should instead be able to explain what becomes better understood if the project succeeds.
The literature review should have changed the idea
One sign that an idea is maturing is that reading no longer merely produces more references. It changes how you formulate the problem.
You begin recognizing:
- which concepts need distinction;
- what researchers already know reasonably well;
- where evidence is inconsistent or limited;
- which populations and contexts have been studied;
- how key constructs have been measured;
- what methodological difficulties recur; and
- which claims remain unsupported or uncertain.
The literature therefore helps transform “I am interested in this” into “this is the particular uncertainty my study could address.”
You do not need an exhaustive review of every publication before design begins. Literature engagement continues throughout research. You do need enough familiarity to avoid designing a study around a question that existing evidence has already answered adequately or framing a supposed research gap that disappears after a basic search.
You should know what kind of claim you hope the study can support
Before choosing a design, ask what you eventually want to be able to say.
Do you want to describe a population? Explore experiences? Estimate an association? Compare groups? Examine change over time? Evaluate an intervention? Develop an explanation? Understand a process? Generate a theory? Assess feasibility?
These are different inferential ambitions.
For example:
| Intended claim |
Evidence implication |
| Describe current practices |
Requires evidence capable of representing those practices in the intended population or cases. |
| Understand experiences or meanings |
Requires evidence that provides appropriate access to participants' accounts, practices, interactions, or relevant contexts. |
| Compare groups |
Requires meaningful comparison groups and appropriate measurement across them. |
| Examine change |
Requires evidence with an appropriate temporal structure. |
| Estimate an association |
Requires appropriate measures of the relevant variables and consideration of alternative explanations. |
| Evaluate an intervention |
Requires a design capable of supporting the intended evaluative or causal inference. |
| Assess feasibility |
Requires evidence about the specific uncertainties that determine whether a later study or intervention can work. |
If you cannot yet articulate the intended claim, comparing designs will be difficult because you have no clear criterion for deciding which design is appropriate.
You should be able to identify the evidence the question would require
This is perhaps the strongest readiness test.
Ask:
If I wanted to answer this question convincingly, what would I need to observe, measure, ask, compare, collect, or obtain?
You do not yet need the final instrument or dataset.
You should be able to identify the broad evidence requirement.
For example:
- students' reported practices;
- actual performance under different conditions;
- interview accounts of decision-making;
- institutional policy documents;
- longitudinal observations;
- administrative records;
- classroom interactions;
- experimental outcomes; or
- several forms of evidence whose integration serves a specific purpose.
If every form of evidence seems equally appropriate, the question may still be too broad.
You should know who or what can provide that evidence
Once the evidence requirement is clearer, identify its plausible source.
If you need students' experiences, which students? If you need institutional policy, which institutions and which documents? If you need academic outcomes, where do those data exist? If you need evidence of change, when must observations occur?
You do not need final eligibility criteria yet. You do need a plausible evidence source.
A project that depends on “university students somewhere” or “institutional data if I can find some” may not yet be ready for detailed design.
Check whether the evidence is obtainable before falling in love with the design
A theoretically elegant study can fail because the necessary evidence cannot realistically be obtained.
Before detailed design, investigate major feasibility assumptions.
Ask:
- Can the intended population realistically be reached?
- Does the necessary dataset exist?
- Can you obtain access to it?
- Can the construct be measured or observed appropriately?
- Can the intervention or procedure be delivered?
- Is the necessary equipment available?
- Does the team have or can it obtain the required expertise?
- Can the study fit within the available time?
- Are there obvious ethical or institutional barriers?
You do not need every permission already granted at this stage. You do need enough information to avoid building the entire design around an implausible assumption.
Distinguish feasibility uncertainty from unresolved methodology
Sometimes researchers think they have a design problem when they actually have an access problem.
You may know that interviews are appropriate but not know whether the intended participants can be recruited. You may know which administrative records would answer the question but not whether the institution will provide access.
Those uncertainties do not necessarily require redesign yet. They require feasibility information.
Conversely, having easy access to participants does not tell you what design should be used. Convenience of access is a feasibility consideration, not a substitute for methodological reasoning.
The scope should be narrow enough that the design does not need to solve several studies at once
An idea is not ready for study design if the intended project still contains several different research projects under one title.
Suppose you want to investigate:
the prevalence, causes, effects, ethics, institutional policies, student experiences, instructor attitudes, and future implications of generative AI in higher education.
No single design choice can resolve that scope problem.
Before detailed methodology, decide what belongs in the project and what does not.
If the project remains too ambitious, identify the minimum defensible study that keeps the research manageable without oversimplifying the science.
The question and available resources should be broadly compatible
A research idea may be scientifically worthwhile and still be inappropriate for the resources available to the current project.
A doctoral research program, a twelve-week undergraduate project, and a five-year funded multicenter study can reasonably pursue different versions of the same broad problem.
Before study design, consider:
- time;
- budget;
- researcher availability;
- team size;
- methodological expertise;
- access to populations or data;
- equipment and software;
- institutional support; and
- fixed submission or graduation deadlines.
These constraints should shape the design without being allowed to justify a design incapable of answering the question.
If the resources and question are incompatible, revise the question, scope, resources, or intended project before proceeding.
Do not choose quantitative, qualitative, or mixed methods as an identity
Researchers sometimes begin with statements such as:
“I want to do quantitative research.”
or:
“I prefer qualitative research.”
Methodological expertise and preference are legitimate practical considerations. They should not be the primary reason a design is selected.
The more useful sequence is:
question → intended claim → required evidence → methodological approach
If the question concerns how participants interpret a complex experience, qualitative evidence may be appropriate. If the question requires estimating a quantity or relationship in a defined population, quantitative evidence may be appropriate. If the question genuinely requires integration of different forms of evidence, mixed methods may be justified.
The label should emerge from the research logic.
Do not choose a survey simply because it is easy to distribute
Surveys are attractive because online tools make them appear operationally simple.
But a survey can answer only questions for which self-reported or measured questionnaire data are appropriate evidence.
If the question concerns actual behavior, complex decision processes, causal effects, organizational practices, or change over time, a one-time self-report survey may be insufficient.
Ease of administration should help choose among scientifically appropriate options, not determine which question the study pretends to answer.
Do not choose interviews merely because the topic is exploratory
“The topic has not been studied much, therefore I will interview people” is also incomplete reasoning.
Interviews are useful when participants' accounts can provide appropriate evidence about experiences, interpretations, reasoning, practices, or processes relevant to the question.
Some understudied questions require measurement, observation, experiments, document analysis, existing data, or other forms of evidence instead.
Exploratory purpose does not automatically imply a particular data collection technique.
Do not choose mixed methods because you cannot decide
Mixed-methods research does not solve uncertainty about methodology by allowing you to choose everything.
It creates an additional design problem: why are multiple forms of evidence needed, how will the components relate, and what will their integration contribute?
If the quantitative and qualitative components could be separated into two unrelated studies without losing anything important, the rationale for mixed methods may be weak.
A mixed design becomes meaningful when integration itself helps answer the research question.
You do not need the final sample yet
Readiness for study design should not be confused with completion of study design.
At this transition point, you may know the relevant population without knowing the final sample size or sampling procedure.
Those decisions depend on the design.
A probability survey, randomized experiment, qualitative interview study, ethnography, case study, and secondary-data analysis use different sampling logics. Finalizing sample details before choosing the broad design can therefore put the sequence backward.
You should know enough to say who or what could provide the evidence. The detailed sampling strategy comes next.
You do not need the final instrument yet
Likewise, you may know that writing self-efficacy needs to be measured without having selected the exact instrument.
Or you may know that interviews need to explore instructors' decision-making without having written the final interview guide.
That is sufficient for the transition into design.
Instrument selection and development should follow once the study's methodological structure, population, constructs, and procedures are clearer.
You do not need the final analysis plan yet
You should understand the broad analytical implications of the question, but the exact analysis may depend on design choices not yet made.
For example, knowing that the question concerns group differences is enough to recognize the need for comparative evidence. The eventual statistical model will depend on measurement, sampling, data structure, assumptions, and other design decisions.
For qualitative research, you may know that the study requires systematic interpretation of interview accounts without having finalized every coding procedure.
The analysis should become progressively more specific as the design develops.
You do not need the complete research protocol yet
A protocol is where the study becomes operationally explicit.
If you are only now deciding among plausible designs, requiring a finalized protocol would put detailed operational planning before the methodological architecture exists.
Once the broad design is selected and sufficiently developed, the project can move toward creating a research protocol.
Drafting a working protocol earlier can still help organize thinking. Just do not mistake a detailed document for a settled study when its foundational design remains unresolved.
You do not need every uncertainty resolved
Moving into study design does not mean planning has ended.
It means the remaining questions can now be addressed through design work.
You may still need to determine:
- the precise sampling strategy;
- sample size or sampling adequacy;
- specific measures;
- interview or observation procedures;
- assignment or comparison procedures;
- data-management details;
- analysis methods;
- quality-control procedures;
- ethics documentation;
- operational timeline; and
- responsibilities.
Those are not signs that the idea is unready. They are the substance of study design and protocol development.
What should already be reasonably stable?
Before moving forward, several foundations should no longer be completely open.
| Foundation |
Ready enough when... |
| Research problem |
You can explain the specific uncertainty or problem the study addresses. |
| Research question |
It is focused enough to identify relevant evidence. |
| Contribution |
You can explain what becomes better understood if the question is answered. |
| Key concepts or phenomena |
You understand them well enough to recognize what must be observed, measured, elicited, or compared. |
| Intended claim |
You know broadly what kind of conclusion the study hopes to support. |
| Evidence requirement |
You can identify the broad form of evidence needed. |
| Evidence source |
There is a plausible population, setting, dataset, material, or other source. |
| Scope |
The project is bounded enough to represent one coherent study or a deliberately integrated design. |
| Feasibility |
No obvious constraint makes all plausible designs unrealistic. |
If several of these remain completely unresolved, additional planning is probably more useful than choosing instruments or statistical tests.
Use competing designs as a readiness test
One useful way to test whether the idea is mature enough is to sketch two or three plausible study designs.
Do not develop them fully. Ask what each would allow you to learn.
For example, suppose your question concerns how university students decide whether generative AI use is academically acceptable.
You might consider:
- a qualitative interview study;
- a vignette-based survey examining judgments across scenarios; or
- a mixed design combining patterned judgments with interviews about the reasoning behind them.
You can now compare them according to the question:
- What evidence does each produce?
- Which aspect of the question can each answer?
- What can each not answer?
- What assumptions does each make?
- What resources does each require?
- Which is feasible?
If you can make this comparison meaningfully, the idea is probably ready for study design.
If every design seems equally suitable because the question is still “AI in education,” return to conceptual planning.
Feasibility should constrain the set of defensible designs, not select an indefensible one
Suppose the strongest design for a particular causal question would require resources you do not have.
The response should not be to conduct an easy cross-sectional survey and interpret it as though it answered the causal question.
Instead, you have several legitimate options:
- narrow or change the research question;
- seek additional resources;
- use a different defensible design that supports a more limited claim;
- conduct a feasibility study;
- use an appropriate existing data source; or
- postpone the question for a future project.
The study you can conduct and the claim you want to make have to remain compatible.
Ethical feasibility belongs in the design-readiness assessment
A study idea should not proceed into elaborate design without considering whether its central premise creates obvious ethical problems.
For human-participant research, the World Medical Association's Declaration of Helsinki states that medical research involving human participants must be scientifically sound and designed to generate reliable and valid knowledge while protecting participants' rights and interests. It also requires foreseeable risks and burdens to be assessed against potential benefits before research begins.
The Declaration applies specifically to medical research involving human participants, so its provisions should not be treated as the governing standard for every discipline. The broader planning lesson is relevant: scientific design and ethical feasibility are connected.
If the research question can be answered only through procedures that would be unacceptable or impossible under the applicable ethical framework, the idea needs reconsideration before detailed design.
Do not confuse design readiness with ethics readiness
At this stage, you are deciding whether the idea is mature enough to develop into a study design. That does not mean the project is ready for ethics submission or data collection.
Those later stages require considerably more detail.
The progression might look like this:
Research idea A potentially worthwhile phenomenon or problem has been identified.
Design-ready idea The question, intended contribution, evidence requirement, scope, and broad feasibility are sufficiently clear to compare methodological options.
Developed study design The methodological architecture, population or evidence source, sampling logic, measurement or data collection, and analytical direction are specified.
Operational protocol The study procedures, instruments, data management, ethics, responsibilities, timeline, and other implementation details are sufficiently documented.
Authorized and operationally ready study Applicable approvals, access, systems, personnel, materials, and other prerequisites are in place for the relevant research activity.
Each transition requires more specificity. Moving into study design is therefore an important commitment, but not the final readiness gate.
Watch for signs that you are moving into design too early
You may be premature if:
- the research question changes fundamentally every few days;
- you cannot explain what evidence would answer it;
- the intended population or phenomenon remains undefined;
- you are selecting methods mainly because you already know the software;
- you are choosing an instrument before deciding what needs to be measured;
- the project still contains several unrelated research questions;
- you have not investigated whether the necessary evidence is accessible; or
- the only reason for choosing the design is that it fits the deadline.
These signs do not mean the idea is poor. They mean additional conceptual or feasibility work may improve the eventual design.
Watch for the opposite problem: refusing to enter design until everything is known
You can also remain in planning too long.
You do not need to know the exact sample size before comparing designs. You do not need the final questionnaire before deciding whether a survey is appropriate. You do not need a completed ethics application before developing the methodology.
If the question, contribution, evidence requirements, scope, and broad feasibility are reasonably clear, many remaining uncertainties are precisely what study design is supposed to resolve.
At that point, additional abstract planning may have diminishing returns.
The project should move forward.
Use a design-readiness gate
Rather than relying on a feeling that the idea is “developed enough,” use explicit criteria.
Question readiness Can I state a focused research question that identifies what needs to be learned?
Contribution readiness Can I explain why answering the question would add useful knowledge or inform a meaningful problem?
Evidence readiness Can I describe the broad evidence needed to answer the question?
Source readiness Can I identify a plausible population, setting, dataset, material, or other source of that evidence?
Scope readiness Is the project bounded enough to become a coherent study rather than a collection of related studies?
Feasibility readiness Is there at least one plausible methodological route that appears compatible with available time, access, resources, expertise, and ethical constraints?
If the answer is yes across these areas, detailed study design is likely the next useful activity.
The transition should change the questions you are asking
During idea development, you ask:
What is worth studying? What exactly do I want to know? Why does it matter? What evidence would answer it? Is the project plausible?
During study design, the questions become:
Which design best generates that evidence? Who or what should be included? How should they be selected? What should be measured or observed? When should data be collected? What comparisons are needed? How will the evidence be analyzed?
That shift is the clearest conceptual marker that planning has done enough of its initial job.