Network design and hat matrix of an illustrative network meta-analysis. In a), the network design of an illustrative example is given: six treatments and eight different observed designs based on two-armed studies. The nodes correspond to the treatments, and the edges show which treatments are directly compared. The thickness of an edge represents the inverse standard error , which is equal one for all designs. In b), the resulting hat matrix at the design level is given in percent, which indicates the contribution of the direct estimate in design d (shown in the column) to the network estimate in design d’ (shown in the row). In addition, the absolute values of the matrix elements are visualized by the area of the gray squares.
Krahn et al. BMC Medical Research Methodology 2013 13:35 doi:10.1186/1471-2288-13-35