Сравнение на методи

	Удобно извадково подбиране на базата на полеви наблюдения	Систематична извадка
Област	Методология на проучванията	Методология на проучванията
Семейство	Process / pipeline	Process / pipeline
Година на възникване	Mid-20th century onward	Mid-20th century (Cochran 1953; Kish 1965)
Създател	Conventional practice in social and epidemiological field research	William G. Cochran; formalized in survey sampling theory
Тип	Non-probability sampling	Probability sampling design
Основополагащ източник	Babbie, E. (2010). The Practice of Social Research (12th ed.). Wadsworth Cengage Learning. ISBN: 978-0495598428	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407
Други названия	intercept sampling, on-site convenience sampling, street intercept sampling, field intercept survey	interval sampling, systematic random sampling, equal-interval sampling, fixed-interval sampling
Свързани	4	5
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.	Systematic sampling is a probability sampling technique in which every k-th element is selected from an ordered list of the population after a random starting point. With population size N and desired sample size n, the sampling interval k = N/n is computed and one unit is chosen at random from the first interval; all subsequent units are selected by adding k repeatedly. The method is operationally simple, yields a spread-out sample, and often achieves lower variance than simple random sampling when the list has no harmful periodicity.