It seems that what stats (LD[0][1] ) calculates when it's supposed to
calculate D is actually |D|
!
I don't know why, but it always returns a positive value...
In the multi-allele case, D is calculated by \sum \sum |D_ij| p_i p_j
and it is always positive. This is how D is implemented in simuPOP and
you will always get |D| evn in the diallelic case.
I can not remember clearly now but D=Pij - Pipj seems to be allele
dependent. I.e., D might be positive or negative depending on which
two alleles you choose. If this is true, |D| does make sense.
Bo
