1. Qualitative, quantitative, or mixed?
Your question’s shape — “how many / how much” vs “how / why” — points to your methodology.
Research design: a plain-English guide
Your research design is the plan that connects your question to your evidence — the choices that decide whether your study can actually answer what you asked. Get these decisions right early and everything downstream (analysis, writing, defending it) gets easier. This guide walks through the core ones.
The design decisions, in order
Design isn’t one choice — it’s a sequence, and each one narrows the next:
2. Which design type?
Experimental, cross-sectional, longitudinal, case study, correlational — each answers a different kind of question.
3. Who, and how many? (sampling)
Probability vs non-probability sampling, and how to choose a method that matches your goal.
Free tool: Sample Size Calculator
4. Variables & hypotheses
Independent vs dependent variables, and how to operationalize them so they can actually be measured.
Free tool: Hypothesis Testability Checker
5. Validity & reliability
The two quality criteria every examiner checks — measuring the right thing, and measuring it consistently.
Free tool: Cronbach’s α calculator
More research-design guides
The concepts and named designs that come up once you start writing the methodology chapter:
Methodology vs methods
Methods are the techniques; methodology is the justification for why they fit. Confusing them is one of the most-penalised thesis errors.
Free tool: Methods Checker
Research paradigms
Positivism, interpretivism, pragmatism — their assumptions, the methods each favours, and how your paradigm justifies your whole design.
Case study research
What a case is, the types, how to bound it, and how to answer the “you can’t generalise” critique.
Cross-sectional vs longitudinal
A snapshot vs the same subjects over time — what each tells you about change and causation, and the trade-offs.
How it all fits together
The chain runs: a clear question → a methodology (qual/quant/mixed) → a design type → a sampling plan → measurable variables → and throughout, attention to validity and reliability. A common failure is jumping to a method (“I’ll run a survey”) before the question demands it. Let the question lead, and the design follows.
Use the tools as you plan
- Research Question Validator — pressure-test the question your design serves.
- Sample Size Calculator & Power Calculator — how many participants.
- Mixed-Methods Design Selector and Randomization Generator.
- Hypothesis Testability Checker — is your hypothesis falsifiable?
Get the free Research Design toolkit
Design-selection flowcharts, sampling and validity checklists, and worked examples from Research Design Simplified. We’ll email you the download link.
Frequently asked questions
What is a research design?
The overall plan for answering your research question — the methodology, the type of study, who you sample, what you measure, and how you guard validity and reliability.
What comes first — method or question?
The question. Choosing a method before the question demands it is the most common design mistake. Let the question’s shape point to the methodology.
Do I need statistics to choose a design?
Not to choose it — but a quantitative design needs a sample-size/power plan, which the statistics guide and the free calculators cover.