[1] The formula for the sampling fraction is where n is the sample size and N is the population size.
A sampling fraction value close to 1 will occur if the sample size is relatively close to the population size.
To correct for this dependence when calculating the sample variance, a finite population correction (or finite population multiplier) of (N-n)/(N-1) may be used.
If the sampling fraction is small, less than 0.05, then the sample variance is not appreciably affected by dependence, and the finite population correction may be ignored.
[2][3] This statistics-related article is a stub.