Review on Research Methods: Conceptions, Fundamentals, Issues and Illustrations

Research Methods can be categorized as quantitative, qualitative and mixed approaches/methods and each methods of research have sub categories. Quantitative research methods are systematic approaches that seek to measure, quantify, and analyze phenomena using numerical data and statistical techniques. They are grounded primarily in positivist or post-positivist philosophical paradigms, emphasizing objectivity, hypothesis testing, measurement, and the identification of relationships among variables. Quantitative research enables researchers to generalize findings from representative samples to broader populations through rigorous sampling procedures and statistical inference. Three major quantitative research approaches are experimental research, which examines cause-and-effect relationships through manipulation and control of variables; survey research, which collects standardized data from large populations using questionnaires or structured interviews; and correlational research, which investigates the strength and direction of relationships among variables without manipulating them. Other common quantitative approaches include causal-comparative (ex post facto), longitudinal, cross-sectional, and descriptive research. 

Qualitative research methods are interpretive and exploratory approaches designed to understand human experiences, meanings, beliefs, cultures, and social interactions within their natural settings. Rooted in constructivist, interpretivist, and critical paradigms, qualitative research emphasizes participants' perspectives and the contextual nature of social phenomena. Rather than relying on numerical measurements, researchers collect rich textual, visual, or audio data through interviews, observations, focus groups, and document analysis. Three widely recognized qualitative research approaches are phenomenology, which explores individuals' lived experiences of a particular phenomenon; ethnography, which investigates the shared culture, behaviors, and practices of groups through prolonged field engagement; and case study research, which provides an in-depth examination of a bounded system, event, organization, or individual within its real-life context. 

Mixed methods research integrates quantitative and qualitative approaches within a single study or a series of related studies to provide a more comprehensive understanding of complex research problems than either approach alone. This methodology is based largely on pragmatic philosophy, recognizing that different research questions may require different forms of evidence and that combining numerical and qualitative data enhances the depth, validity, and practical relevance of research findings. Mixed methods research intentionally integrates data collection, analysis, and interpretation from both methodological traditions to achieve triangulation, complementarity, development, or expansion of findings. Three major mixed methods research approaches are the convergent parallel design, in which quantitative and qualitative data are collected simultaneously and integrated during interpretation; the explanatory sequential design, where quantitative findings are collected first and subsequently explained through qualitative investigation; and the exploratory sequential design, which begins with qualitative exploration followed by quantitative testing or validation.