英语翻译A dyadic relationship is undirectional if Y(ji) = Y(ij)

英语翻译
A dyadic relationship is undirectional if Y(ji) = Y(ij) for all i; j.In this case,symmetry requires that
regressors satisfy DX(ij) = DX(ji).One easy way of satisfying this requirement is to specify the regression
as:
where Z(i) and Z(j) are characteristics of individual i and j thought to infuence the likelihood of a link Y(ij)
between them.Coeffcient D(1) measures the effect of differences in attributes on Y(ij) while D(2) captures the
effect of the combined level of Z(i) and Z(j) on Y(ij) .If a dyadic relationship is directional,Yij needs not equal
Yji.In this case,the symmetry requirement can be satis…ed by specifying the model as:
For D2 to be identified,individuals must not have the same number of links----see Marcel Fafchamps and
Flore Gubert (2006) for details.