a Although we categorized Expert Opinion as a fully
independent data source, it differs from other categories because it is
not empirical (Zeller et al. 2012).
Twenty-two of the 34 studies that validated their current density
(output) models (~65%) reported agreement between model
predictions and validation data, while four (12%) found poor agreement
between model results and validation data. The remaining eight
(~24%) either reported mixed results or were
inconclusive.
After an initial and substantial increase, the proportion of studies
that specified the type of connectivity being modeled leveled off or
even declined in recent years (Figure 2). Studies that implemented some
form of SUA seem to have been slowly increasing, and there has been no
clear trend through time in the proportion of studies validating
connectivity models (Figure 2).