Kelly's ZnS
Kelly's  is a test statistic that can be used to test a genetic region for deviations from the neutral model, based on the squared correlation of allelic identity between loci. Details 
Given loci  and ,   the Linkage Disequilibrium between these loci, is denoted as

where  is the frequency of the alternative allele at i and j co-occurring and  and  the frequency of the alternative allele at  and  respectively. a standardised measure of this is  the squared correlation of allelic identity between loci  and 

Where   averages   over all pairwise combinations between S loci. Usage 
Inflated  scores indicate a deviation from the neutral model and can be used as a potential signature of previous selection

References 

Statistical hypothesis testing
Neutral theory