Σύγκριση μεθόδων

	Δειγματοληψία ποσοστώσεων	Δειγματοληψία συστάδων
Πεδίο	Μεθοδολογία Επισκοπήσεων	Μεθοδολογία Επισκοπήσεων
Οικογένεια	Process / pipeline	Process / pipeline
Έτος προέλευσης	1930s	Early-to-mid 20th century; canonical treatment 1953/1977
Δημιουργός	Developed in market research and opinion polling, notably applied by George Gallup in the 1930s	Formalized by William G. Cochran; roots in early 20th-century U.S. Census Bureau survey practice
Τύπος	Non-probability sampling design	Probability sampling design
Θεμελιώδης πηγή	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.). Wiley. ISBN: 978-0471162407
Εναλλακτικές ονομασίες	quota-controlled sampling, quota selection, non-probability quota sampling	cluster random sampling, area sampling, one-stage cluster sampling
Συναφείς	5	5
Σύνοψη	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.	Cluster sampling is a probability sampling technique in which the population is divided into naturally occurring groups (clusters), a random sample of clusters is selected, and all — or a random subset of — members within each selected cluster are studied. It is especially practical when a complete population list is unavailable or when units are geographically dispersed, making individual random selection prohibitively expensive. One-stage cluster sampling surveys every member of selected clusters; two-stage designs add a second random draw within clusters.