We now take the average function (Figure 3 (a)) into considerations, as graph clustering algorithm gradually partitions from one cluster (corresponding to threshold 1) to more clusters, the number of query collaborators gradually reduces, meanwhile, the accuracy gradually increases and reaches the highest (73.6%) at threshold of 0.45, which clearly shows that removing noisy collaborators in the query collaboration group can improve the performance.
to traditional non-collaborative ranking scheme which solely relies on the strengths of isolated queries and one stand-alone ranking algorithm, the new scheme integrates the strengths from multiple collaborators of a query and the strengths from multiple ranking algorithms.