Сравнение на методи

	Удобно извадково подбиране на базата на полеви наблюдения	Целенасочено подбиране
Област	Методология на проучванията	Методология на проучванията
Семейство	Process / pipeline	Process / pipeline
Година на възникване	Mid-20th century onward	Formalized ~1980–1990
Създател	Conventional practice in social and epidemiological field research	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
Тип	Non-probability sampling	Non-probability sampling strategy
Основополагащ източник	Babbie, E. (2010). The Practice of Social Research (12th ed.). Wadsworth Cengage Learning. ISBN: 978-0495598428	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
Други названия	intercept sampling, on-site convenience sampling, street intercept sampling, field intercept survey	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
Свързани	4	4
Резюме	Field-based convenience sampling is a non-probability technique in which researchers recruit participants by approaching whoever is physically present and accessible at a chosen real-world location — a market, hospital waiting room, park, or transit hub. It is widely used in public health surveillance, marketing research, and exploratory social surveys when rapid, low-cost data collection is needed and probability sampling is not feasible.	Purposive sampling is a non-probability strategy in which the researcher deliberately selects participants, documents, or cases that are information-rich with respect to the research question. Rather than drawing units at random, the researcher applies explicit criteria aligned with the study's purpose, maximising the depth and relevance of the data collected. It is the default sampling logic in most qualitative research designs and is also used in mixed-methods and applied evaluative work.