To avoid confusion, Fig.1 illustrates the situation to be addressed in this paper. Fig.1(A) is the standard situation where samples are independent. Fig.1(B) shows the situation where all samples are correlated with one another. This is however not the situation we will address. Fig.1(C) consists of correlated clusters, whereas there is no correlation between clusters themselves. Fig.1(C) is the situation when relatives of the same family are used for association analysis.
