Сравнение на методи

	Квотен подбор	Систематична извадка
Област	Методология на проучванията	Методология на проучванията
Семейство	Process / pipeline	Process / pipeline
Година на възникване	1930s	Mid-20th century (Cochran 1953; Kish 1965)
Създател	Developed in market research and opinion polling, notably applied by George Gallup in the 1930s	William G. Cochran; formalized in survey sampling theory
Тип	Non-probability sampling design	Probability sampling design
Основополагащ източник	Moser, C. A., & Kalton, G. (1972). Survey Methods in Social Investigation (2nd ed.). Heinemann. ISBN: 978-0435827496	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407
Други названия	quota-controlled sampling, quota selection, non-probability quota sampling	interval sampling, systematic random sampling, equal-interval sampling, fixed-interval sampling
Свързани	5	5
Резюме	Quota sampling is a non-probability technique in which the researcher pre-specifies how many units to recruit from each subgroup (quota cell) defined by one or more control variables such as age, gender, or occupation. Interviewers or data collectors then use their own judgment to find and enroll participants until each cell is filled. The method guarantees the sample mirrors the population on the control variables but does not provide the randomness needed for classical statistical inference.	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.