Figure 4.

Cumulative coverage plot similarity matrix of selected sources.

Notes: (A) By hovering along the x-axis, the user can choose the set size of the most frequent concepts and immediately see coverage of all concept occurrences. For instance, the 13 most frequent concepts cover 28% of all 108 concept occurrences and the 20 most frequent concepts cover 35%. Those concepts can be viewed in detail within the concept list (see Figures 2 and 3). The dashed diagonal line indicates a possible graph if all the concepts had occurred only once, and thus has a constant linear slope. Therefore, initially high deviation of the actual graph (blue solid line) from the dashed line indicates existence of highly repetitive concepts within the sources. (B) Each cell contains the number of common concepts of two sources. Two additional numbers provide percentages that represent the relative overlap between source 1 and source 2. For instance, the second cell provides concept overlaps between eligibility criteria of studies NCT00592527 and NCT00641251. There are three common concepts, which can be reviewed in detail (see Figures 2 and 3) upon the user clicking. Since the first study contains only 12 concepts and the second 17, the relative overlap is higher in the first study (25.0% vs 17.6%). The redder each cell is, the higher the first percentage value, which indicates the overlap of source 1 in source 2. Blue font indicates the number of common concepts for each cell.