So sánh phương pháp

	Chọn mẫu hạn ngạch	Chọn mẫu có chủ đích
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1930s	Formalized ~1980–1990
Người khởi xướng	Developed in market research and opinion polling, notably applied by George Gallup in the 1930s	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
Loại	Non-probability sampling design	Non-probability sampling strategy
Công trình gốc	Moser, C. A., & Kalton, G. (1972). Survey Methods in Social Investigation (2nd ed.). Heinemann. ISBN: 978-0435827496	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
Tên gọi khác	quota-controlled sampling, quota selection, non-probability quota sampling	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
Liên quan	5	4
Tóm tắt	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.	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.