So sánh phương pháp

	Lấy mẫu lý thuyết dựa trên thực địa	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	1967	Formalized ~1980–1990
Người khởi xướng	Barney G. Glaser and Anselm L. Strauss	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
Loại	Qualitative iterative sampling strategy	Non-probability sampling strategy
Công trình gốc	Glaser, B. G., & Strauss, A. L. (1967). The Discovery of Grounded Theory: Strategies for Qualitative Research. Aldine. ISBN: 978-0202302607	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
Tên gọi khác	field theoretical sampling, in-situ theoretical sampling, fieldwork-driven theoretical sampling, grounded field sampling	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
Liên quan	3	4
Tóm tắt	Field-based theoretical sampling is an iterative qualitative sampling strategy in which decisions about whom to observe or interview next are made during active fieldwork, guided by emerging theoretical insights from the data already collected. Rooted in Glaser and Strauss's grounded theory, it extends theoretical sampling into naturalistic, in-situ field settings — ethnographic sites, clinical environments, organizational contexts — where data collection and analysis proceed simultaneously.	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.