So sánh phương pháp

	Lấy mẫu thuận tiện theo tỷ lệ	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	Mid-20th century onward	Formalized ~1980–1990
Người khởi xướng	Developed within mainstream sampling methodology; no single originator	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
Loại	Non-probability sampling with proportional allocation constraint	Non-probability sampling strategy
Công trình gốc	Etikan, I., & Bala, K. (2017). Sampling and sampling methods. Biometrics & Biostatistics International Journal, 5(6), 215–217.	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
Tên gọi khác	quota-constrained convenience sampling, representative convenience sampling, proportionate accidental sampling, PCS	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
Liên quan	4	4
Tóm tắt	Proportional convenience sampling is a non-probability technique that recruits participants through convenience while constraining each subgroup's share in the final sample to match its known proportion in the target population. It trades pure random selection for feasibility, but partially compensates by ensuring the sample's compositional profile mirrors the population on one or more key variables such as gender, age group, or academic year.	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.