Research Design
Research design is the blueprint for conducting a study. It specifies how data will be collected, measured, and analysed to answer research questions. The design must align with the research objectives and available resources.
Types of Research Design
Exploratory designs investigate new areas with flexible methods (interviews, focus groups). Descriptive designs document characteristics systematically (surveys, observations). Explanatory (causal) designs test cause-effect relationships through experiments or quasi-experiments.
Experimental Design
Experiments manipulate an independent variable and measure its effect on a dependent variable while controlling extraneous variables. Key elements: random assignment, control group, treatment group. Designs include pre-test/post-test, Solomon four-group, and factorial designs. True experiments establish causality.
Survey Design
Surveys collect data from a sample through questionnaires or interviews. They can be cross-sectional (one point in time) or longitudinal (over time). Surveys efficiently gather data from large populations but depend on response rates and honest, accurate answers.
Case Study
A case study examines a single entity (person, organisation, event) in depth using multiple data sources. It provides rich, contextual understanding but has limited generalisability. Case studies are common in software engineering research.
Variables
Independent variables are manipulated or selected; dependent variables are measured outcomes. Extraneous variables are controlled to avoid confounding. Moderating variables influence the strength of a relationship; mediating variables explain the mechanism.
Validity and Reliability
Validity measures whether the study measures what it intends to. Internal validity ensures causal conclusions are justified; external validity ensures generalisability. Reliability means consistent results on repetition. Threats include history, maturation, selection bias, and instrumentation effects.
Summary
Choosing an appropriate research design — experimental, survey, case study, or mixed methods — is crucial for producing valid and reliable findings. The design must fit the research questions, constraints, and ethical requirements.