So sánh phương pháp

	Lấy mẫu ngẫu nhiên đơn giản theo tỷ lệ	Lấy mẫu có hệ thống
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	Mid-20th century (formalized ~1950s–1970s)	Mid-20th century (Cochran 1953; Kish 1965)
Người khởi xướng	William G. Cochran and survey statisticians (classical probability sampling tradition)	William G. Cochran; formalized in survey sampling theory
Loại	Probability sampling technique	Probability sampling design
Công trình gốc	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407
Tên gọi khác	proportional SRS, probability-proportional simple random sampling, proportional random sampling	interval sampling, systematic random sampling, equal-interval sampling, fixed-interval sampling
Liên quan	6	5
Tóm tắt	Proportional simple random sampling is a probability-based sampling technique in which units are drawn at random from each subgroup of the population in numbers proportional to each subgroup's share of the total population. This ensures the resulting sample mirrors the population's composition across key subgroups, while retaining the randomness and unbiasedness of simple random sampling within each group.	Systematic sampling is a probability sampling technique in which every k-th element is selected from an ordered list of the population after a random starting point. With population size N and desired sample size n, the sampling interval k = N/n is computed and one unit is chosen at random from the first interval; all subsequent units are selected by adding k repeatedly. The method is operationally simple, yields a spread-out sample, and often achieves lower variance than simple random sampling when the list has no harmful periodicity.