Association clustering (AC) help us in determining correlation between neighbouring terms. AC lacks distributive correlation property, i.e. if a term t1 is associated to term t2, and term t2 is correlated to term t3, then t1 must be related to t3.
To overcome the drawback of AS, Scalar clustering (SC) is used. Scalar cluster is obtained by taking dot product of 2 term vectors in Association Cluster. SC determines neighbourhood correlation.