MARCH 2, 2001

Rigour in the calculation of sampling error: a design effect calculator

Traditionnally, the calculations of sampling margin of errors have paid little attention to the fact that using non proportional sampling strata increases the variance of the estimates derived from a sample. Yet, as soon as 1965, Leslie Kish (Survey Sampling, John Wiley & Sons) had clearly raised the issue. In an article published in December 2000, Bruce D. Spencer ("An approximate design effect for unequal weighting when measurements may correlate with selection probabilities", Survey Methodology) analyses the issue in depth. Circum Network now offers an interactive, self-documented tool called DeffCalc to compute design effects for various scenarios of distribution of a stratified sample. Your comments concerning this tool are welcome.

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