In sampling theory, the **sampling fraction** is the ratio of sample size to population size or, in the context of stratified sampling, the ratio of the sample size to the size of the stratum.^{[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. When sampling from a finite population without replacement, this may cause dependence between individual samples. 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]}

## References

**^**Dodge, Yadolah (2003).*The Oxford Dictionary of Statistical Terms*. Oxford: Oxford University Press. ISBN 0-19-920613-9.**^**Bain, Lee J.; Engelhardt, Max (1992).*Introduction to probability and mathematical statistics*(2nd ed.). Boston: PWS-KENT Pub. ISBN 0534929303. OCLC 24142279.**^**Scheaffer, Richard L.; Mendenhall, William; Ott, Lyman (2006).*Elementary survey sampling*(6th ed.). Southbank, Vic.: Thomson Brooks/Cole. ISBN 0495018627. OCLC 58425200.

This statistics-related article is a stub. You can help Wikipedia by expanding it. |