Сравнение на методи

	Методи за извадки в изследванията	Формулиране на изследователски въпрос
Област	Методология на изследванията	Методология на изследванията
Семейство	Process / pipeline	Process / pipeline
Година на възникване	1950	1950
Създател	William G. Cochran and Leslie Kish (1950s–1970s)	Kerlinger, Campbell, & Fisher (1950s–1990s research methodology literature)
Тип	Framework	Framework
Основополагащ източник	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons.	Kerlinger, F. N., & Lee, H. B. (1999). Foundations of Behavioral Research (4th ed.). Wadsworth.
Други названия	sampling strategy, sampling design, probability and non-probability sampling	RQF, research question design
Свързани	3	2
Резюме	Sampling is the process of selecting a subset of individuals, observations, or units (the sample) from a larger population to study. Sampling methods are broadly classified into probability (random) and non-probability (non-random) approaches. Probability methods—random sampling, stratified sampling, cluster sampling, systematic sampling—enable statistical inference to the population and allow calculation of confidence intervals and margins of error. Non-probability methods—convenience, purposive, snowball, quota sampling—are practical for exploratory or qualitative research but do not support formal statistical generalization. Cochran's Sampling Techniques (1977) and Kish's Survey Sampling (1965) are foundational references; modern applications span surveys, experiments, qualitative studies, and clinical trials.	Research question formulation is the process of defining clear, focused, and answerable questions that guide a research study. A well-formulated research question specifies what a researcher seeks to investigate, distinguishing between independent and dependent variables (or phenomena), and sets the scope for literature review, methodological design, and data collection. Established in behavioral research literature in the mid-20th century, this framework remains foundational because it transforms vague research interests into testable, empirically grounded inquiries.