Data Collection Methods

Data collection methods are the specific techniques and instruments used to gather information from research participants or sources. Common quantitative methods include surveys (questionnaires, interviews), physiological measurements (blood pressure, lab assays), behavioral observations, and administrative/secondary data (e.g., medical records, national registers). Qualitative methods include in-depth interviews, focus groups, observations, and document analysis. Selection and design of data collection instruments directly affect data quality, validity, and reliability. Floyd Fowler's work on survey methodology (1980s–2010s), Robert DeVellis's scale development approach, and John Creswell's frameworks for qualitative data collection provide systematic guidance.