Nursing research falls into four families. Quantitative designs (experimental, quasi-experimental, correlational, observational) test hypotheses using numerical data. Qualitative designs (phenomenology, grounded theory, ethnography, qualitative description) explore meaning and experience. Mixed methods integrate both. Evidence syntheses (systematic, integrative, and scoping reviews) combine existing studies. Choose a design by matching it to your research question: 'does X cause Y' points to an experiment, 'what is it like' points to phenomenology, and 'what process explains' points to grounded theory.
Research design comparison matrix
| Design | Family | Paradigm | Core feature | Evidence level* |
|---|---|---|---|---|
| Randomized controlled trial | Quantitative | Postpositivist | Random assignment to intervention/control | Level II |
| Quasi-experimental | Quantitative | Postpositivist | Intervention without randomization (e.g., pre/post) | Level III |
| Descriptive correlational | Quantitative | Postpositivist | Relationships among variables, no manipulation | Level IV–VI |
| Cohort / case-control | Quantitative | Postpositivist | Observational comparison over time or by outcome | Level IV |
| Descriptive phenomenology (Husserl) | Qualitative | Interpretivist | Essence of lived experience; bracketing | Level VI |
| Interpretive phenomenology (Heidegger) | Qualitative | Interpretivist | Meaning of being-in-the-world; hermeneutic circle | Level VI |
| Grounded theory | Qualitative | Symbolic interactionism | Generates theory from data; constant comparison | Level VI |
| Ethnography | Qualitative | Interpretivist | Culture of a group; fieldwork and observation | Level VI |
| Mixed methods (convergent, explanatory, exploratory) | Mixed | Pragmatist | Integrates quantitative and qualitative strands | Varies |
| Delphi study | Consensus | Pragmatist | Iterative expert rounds to reach agreement | Level VII |
| Systematic review / meta-analysis | Synthesis | Postpositivist | Exhaustive, protocol-driven synthesis of studies | Level I |
| Scoping review | Synthesis | Pragmatist | Maps breadth of evidence; no quality appraisal required | Varies |
Quantitative research methods in nursing
Quantitative designs answer questions about cause, effect, prevalence, and association. Rigor is judged by internal validity, external validity, reliability (Cronbach's α ≥ .70 for instruments), and adequate statistical power (usually 0.80, computed in G*Power).
- Experimental: randomization, manipulation, and control. Example: chlorhexidine bathing vs. soap and water on CLABSI rates.
- Quasi-experimental: manipulation without randomization — the most common DNP project design (pre/post with comparison group).
- Correlational: examines relationships, e.g., nurse staffing and patient falls.
- Descriptive: characterizes a phenomenon, e.g., prevalence of burnout among ICU nurses.
Sampling: probability sampling (simple random, stratified, cluster) supports generalization; convenience sampling is common but limits external validity.
Qualitative research methods in nursing
Qualitative designs explore meaning, experience, and social process. Rigor is judged by Lincoln and Guba's trustworthiness criteria: credibility, transferability, dependability, and confirmability (plus authenticity).
- Husserlian phenomenology: describes the essence of an experience; researcher brackets preconceptions. Analysis: Colaizzi or Giorgi.
- Heideggerian phenomenology: interprets meaning; researcher's pre-understanding is acknowledged. Analysis: van Manen or IPA.
- Grounded theory: builds a theory of a social process. Glaserian, Straussian, or constructivist (Charmaz) variants; theoretical sampling until saturation.
- Ethnography: studies the culture of a unit or community through participant observation.
- Qualitative descriptive (Sandelowski): straightforward description close to participants' words — ideal for practice-focused questions.
Sampling is purposive; sample size is determined by saturation (often 10–30 interviews).
Mixed methods and evidence synthesis
Creswell and Plano Clark's three core mixed-methods designs: convergent (both strands at once, merged), explanatory sequential (quantitative first, qualitative explains), and exploratory sequential (qualitative first, builds an instrument or hypothesis).
Reviews: systematic reviews follow PRISMA 2020 and a registered protocol (PROSPERO); integrative reviews (Whittemore & Knafl) combine diverse designs; scoping reviews follow JBI and PRISMA-ScR to map a field.
Methodology chapter blueprint
- Problem and purpose restated with the research question(s) or hypotheses.
- Design and justification — why this design fits the question and paradigm better than alternatives.
- Setting and sample — population, inclusion/exclusion criteria, sampling method, power analysis or saturation rationale.
- Instruments / data collection — validity and reliability evidence, or interview guide and field procedures.
- Data analysis — statistical tests matched to variables, or qualitative analytic method step by step.
- Rigor — threats to validity, or trustworthiness strategies (member checking, audit trail, reflexivity).
- Ethics — IRB approval, informed consent, data protection, risk mitigation.
- Limitations stated honestly.
Frequently Asked Questions
Sources & Further Reading
- Nursing Research: Generating and Assessing Evidence for Nursing Practice. Polit, D. F., & Beck, C. T. (11th ed.). Wolters Kluwer, 2021.
- Evidence-Based Practice in Nursing & Healthcare. Melnyk, B. M., & Fineout-Overholt, E. (5th ed.). Wolters Kluwer, 2023.
- Designing and Conducting Mixed Methods Research. Creswell, J. W., & Plano Clark, V. L. (3rd ed.). SAGE, 2018.
- Naturalistic Inquiry. Lincoln, Y. S., & Guba, E. G. SAGE, 1985.