Designing a Study You Can Defend
A useful deviation report tells readers what was preregistered, what actually happened, why the change occurred, and when the decision was made. The goal is to make differences easy to find and interpret rather than forcing readers to reconstruct them.
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Designing a Study You Can Defend
Between-subjects designs compare different participants across conditions, while within-subjects designs compare conditions within the same participants. The better choice depends on what is being studied and whether experiencing one condition can influence another.
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Designing a Study You Can Defend
Recruitment problems do not automatically mean that a study has failed. Diagnose why recruitment is falling short before changing the strategy, because some solutions can alter the sample, introduce bias, or change the study itself.
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Designing a Study You Can Defend
Falling short of a planned sample size does not automatically make a study worthless, but it may substantially change what the data can establish. The appropriate response is to assess the consequences of the smaller sample rather than retroactively making the original target disappear.
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Designing a Study You Can Defend
A control or comparison group can fail to function as intended even when recruitment and data collection continue normally. The key is to determine what actually happened in each group, why it happened, and whether the intended comparison still supports the study's research question.
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Designing a Study You Can Defend
The people you can recruit are not always the people you originally intended to study. Before broadening eligibility or changing recruitment settings, determine whether the accessible population can still provide evidence relevant to the original research question.
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Designing a Study You Can Defend
A method can be implemented perfectly and still be wrong for the question it is supposed to answer. When that mismatch becomes apparent, reassess what evidence the question requires before deciding whether to adapt the method, narrow the question, or redesign the study.
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Designing a Study You Can Defend
Not every methodological change creates a new study, but some changes alter the research question, evidence, population, comparison, or inferential logic so substantially that treating the project as unchanged becomes misleading. The boundary is conceptual, not a fixed percentage of procedures changed.
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Designing a Study You Can Defend
Not every change to a research sample creates a different study. The critical issue is whether the revised sample still provides evidence about essentially the same population and research question, or whether the change alters what the study is actually about.
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Designing a Study You Can Defend
Not every tiny departure from a research plan deserves equal space in a publication, but deviations that affect interpretation, participant protections, planned analyses, or confidence in the findings generally should be visible. The goal is to let readers understand the study that was actually conducted.
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Designing a Study You Can Defend
Every real study operates under constraints, so some methodological compromise is unavoidable. The critical question is whether the remaining design can still support the claims you intend to make after those compromises are considered together.
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Designing a Study You Can Defend
Case study research investigates a clearly bounded case in depth and in relation to its real-world context. Studying one person, classroom, institution, event, or site does not automatically make a project a case study because the design depends on how the case is defined and investigated.
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Designing a Study You Can Defend
Mixed methods research requires more than collecting qualitative and quantitative data in the same project. The defining issue is whether the components are deliberately related and integrated to produce an understanding that neither component would provide independently.
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Designing a Study You Can Defend
A study does not become mixed methods simply because its dataset contains both numbers and words. What matters is whether substantive qualitative and quantitative components are intentionally designed, analyzed, and integrated to address the research problem.
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Designing a Study You Can Defend
Not every research question needs two groups, two treatments, or a before-and-after comparison. The comparison should follow from what you want to know, not from the assumption that stronger research always compares something.
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Designing a Study You Can Defend
Correlation, association, prediction, and causation answer different research questions. Learn how to match the claim you want to make with the evidence your study is actually designed to provide.
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Designing a Study You Can Defend
A causal question asks what would have happened under an alternative condition. That unobserved alternative is the counterfactual, and constructing a credible substitute for it is central to causal research.
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Designing a Study You Can Defend
Observational data do not automatically restrict researchers to non-causal questions. Causal inference may be possible when the causal contrast, design, assumptions, timing, confounding strategy, and analysis are explicitly aligned.
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Designing a Study You Can Defend
A defensible sample begins with a clearly defined population. Learn how to move from your research question to the people or units you actually recruit without claiming more than your design can support.
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Designing a Study You Can Defend
Your data usually come from a sample, but your research question may concern a much larger population. Understanding that distinction is essential for choosing participants and interpreting what your findings actually mean.
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Designing a Study You Can Defend
A sampling frame is the operational source from which a sample is selected, but it may not perfectly match the population you want to study. Learn how frame errors can quietly change who has a chance to enter your sample.
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Designing a Study You Can Defend
More participants can improve statistical precision and power, but sample size is only one part of research quality. A large sample cannot automatically repair biased recruitment, poor measurement, confounding, or a weak design.
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Designing a Study You Can Defend
A representative sample is meaningful only in relation to a specified population. Learn what representativeness actually requires, how researchers assess it, and why not every worthwhile study needs a statistically representative sample.
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Designing a Study You Can Defend
A large sample can reduce random uncertainty while leaving systematic bias almost untouched. Learn why thousands or even millions of observations can produce extremely precise answers to the wrong population question.
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Designing a Study You Can Defend
There is no universal number of participants that makes a quantitative study adequately powered. Learn what determines sample size, how statistical power fits into the calculation, and why the planned analysis should come before the final number.
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