An assignment test is a statistical calculation to group individuals based on genotype. The test uses individual genotypes and alleles to assign an individual to the population it has the highest probability of belonging to (Paetkau et al. 1995). When the organisms are dispersed among connected but spatially distinct populations (such as islands), assignment tests can estimate movement of genetic information (Remais et al. 2011). Assignment tests use allele frequencies of different populations at different loci to calculate the statistical probability that an individual belongs to a population. The population that has the highest likelihood is the population where the individual is assigned (Paetkau et al. 1995).
Several errors are possible with the assignment test. The first is the cross-assignment percentage which occurs when an individual is assigned to a population other than the one that they were sampled from (Abdelkrim et al. 2005). Other technical issues can affect the statistical test. These include incorrect genotyping and poor field sampling techniques (Antolin, M. 2012).
Abdelkrim, J., Pascal, M., Calmet, C., & Samadi, S. (2005). Importance of Assessing Population Genetic Structure before Eradication of Invasive Species: Examples from Insular Norway Rat Populations. Conservation Biology, 19(5), 1509–1518. doi:10.1111/j.1523-1739.2005.00206.x
Antolin, M. (2012). Assignment tests and population genetics. Colorado State University.
Paetkau, D, W. Calvert, I. Stirling, and C. Strobeck. 1995. Microsatellite analysis of population structure in Canadian polar bears. Mol. Ecol. 4: 347-354
Remais, J. V., Xiao, N., Akullian, A., Qiu, D., & Blair, D. (2011). Genetic Assignment Methods for Gaining Insight into the Management of Infectious Disease by Understanding Pathogen, Vector, and Host Movement. (M. Manchester, Ed.)PLoS Pathogens, 7(4).