So sánh phương pháp

	Lấy mẫu kép	Lấy mẫu có hệ thống
Lĩnh vực	Lấy mẫu	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1938	Mid-20th century (Cochran 1953; Kish 1965)
Người khởi xướng	Jerzy Neyman	William G. Cochran; formalized in survey sampling theory
Loại	Multi-phase sampling design	Probability sampling design
Công trình gốc	Neyman, J. (1938). Contribution to the theory of sampling human populations. Journal of the American Statistical Association, 33(201), 101–116.	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407
Tên gọi khác	Two-Phase Sampling	interval sampling, systematic random sampling, equal-interval sampling, fixed-interval sampling
Liên quan	4	5
Tóm tắt	Double Sampling (also called two-phase or multistage sampling) is a survey design in which a large preliminary sample is collected using inexpensive methods or partial information, then a smaller subsample is drawn from it and measured in detail. Pioneered by Jerzy Neyman in 1938, it is particularly useful when a cheap surrogate measurement is available but true measurement is expensive.	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.