Sample Size Requirements


Sample size requirements in the context of linkage analysis between a trait and genetic markers refer to the calculation of the sample size required for a linkage study to guarantee a certain power of the study against an assumed inheritance model. The power against an assumed inheritance model is the probability of correctly declaring a linkage when in fact the assumed inheritance model is true and the trait and marker loci are linked.

Keywords: power; inheritance model; parametric linkage analysis; affected sibling pair test; transmission/disequilibrium test


Blackwelder WC and Elston RC (1985) A comparison of sib‐pair linkage tests for disease susceptibility loci. Genetic Epidemiology 2: 85–97.

Feller W (1970) An Introduction to Probability Theory and its Applications, 3rd edn. New York, NY: Wiley.

Knapp M (1999) A note on power approximations for the transmission/disequilibrium test. American Journal of Human Genetics 64: 1177–1185.

Ploughman LM and Boehnke M (1989) Estimating the power of a proposed linkage study for a complex genetic trait. American Journal of Human Genetics 44: 543–551.

Risch N (1990) Linkage strategies for genetically complex traits. II. The power of affected relative pairs. American Journal of Human Genetics 46: 229–241.

Risch N and Merikangas K (1996) The future of genetic studies of complex human diseases. Science 273: 1516–1517.

SAS Institute Inc. (1990) SAS Language: Reference, version 6, 1st edn. Cary, NC: SAS Institute.

Spielman RS, McGinnis RE and Ewens WJ (1993) Transmission test for linkage disequilibrium: the insulin gene region and insulin‐dependent diabetes mellitus (IDDM). American Journal of Human Genetics 52: 502–516.

Suarez BK, Rice J and Reich T (1978) The generalized sib pair IBD distribution: its use in the detection of linkage. Annals of Human Genetics 42: 87–94.

Terwilliger JD, Speer M and Ott J (1993) Chromosome‐based method of rapid computer simulation in human genetic linkage analysis. Genetic Epidemiology 10: 217–224.

Weeks DE, Ott J and Lathrop GM (1990) SLINK: a general simulation program for linkage analysis. American Journal of Human Genetics 47: A204.

Further Reading

Chen WM and Deng HW (2001) A general and accurate approach for computing the statistical power of the transmission disequilibrium test for complex disease genes. Genetic Epidemiology 21: 53–67.

Holmans P (2001) Nonparametric linkage. In: Balding DJ, Bishop M and Cannings C (eds.) Handbook of Statistical Genetics, pp. 541–563. Chichester, UK: Wiley.

Holmans P and Clayton D (1995) Efficiency of typing unaffected relatives in an affected‐sib‐pair linkage study with single‐locus and multiple tightly linked markers. American Journal of Human Genetics 57: 1221–1232.

Krawczak M (2001) ASP – a simulation‐based power calculator for genetic linkage studies of qualitative traits, using sib‐pairs. Human Genetics 109: 675–677.

Risch N (2000) Searching for genetic determinants in the new millennium. Nature 405: 847–856.

Thompson EA (2001) Linkage analysis. In: Balding DJ, Bishop M and Cannings C (eds.) Handbook of Statistical Genetics, pp. 541–563. Chichester, UK: Wiley.

Weeks DE and Lathrop GM (1995) Polygenic disease: methods for mapping complex disease traits. Trends in Genetics 11: 513–519.

Web Links

SAS macro to compute power approximations for the TDT http://www.uni‐∼umt70e/soft.htm

SIMLINK program

SIMULATE program

SLINK program

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Knapp, Michael(Jan 2006) Sample Size Requirements. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0005436]