So sánh phương pháp

	Lý thuyết Nền tảng	Chọn mẫu có chủ đích	Lấy mẫu chuỗi giới thiệu – Lấy mẫu quả cầu tuyết
Lĩnh vực	Nghiên cứu định tính	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline	Process / pipeline
Năm ra đời	1967	Formalized ~1980–1990	1961
Người khởi xướng	Barney Glaser and Anselm Strauss	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry	Leo A. Goodman
Loại	Method	Non-probability sampling strategy	Non-probability sampling technique
Công trình gốc	Glaser, B. G., & Strauss, A. L. (1967). The discovery of grounded theory: Strategies for qualitative research. Aldine.	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796	Goodman, L. A. (1961). Snowball sampling. Annals of Mathematical Statistics, 32(1), 148–170.
Tên gọi khác	GT, Grounded Theory Approach	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling
Liên quan	3	4	3
Tóm tắt	Grounded Theory (GT) is a systematic qualitative research methodology in which theory emerges directly from data through iterative analysis, rather than being imposed before data collection. Developed by Barney Glaser and Anselm Strauss in 1967, GT prioritizes generating explanatory frameworks grounded in evidence.	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.	Snowball sampling is a non-probability recruitment technique in which initial participants (seeds) refer the researcher to others who meet the study criteria, and those referrals in turn refer further participants. The sample grows incrementally — like a rolling snowball — until the required size or theoretical saturation is reached. It is the method of choice when a target population has no accessible sampling frame, such as undocumented migrants, illicit drug users, survivors of stigmatised experiences, or members of closed professional networks.