Exploring and examining assessment data via a matrix visualisation

OPAL (Online PArtner Lens) is an application designed to match project requirements with suitable teams and individuals, and as part of its matching process features an evaluation mechanism designed to elicit measures of trust between potential partners. We describe a matrix-style visualisation that displays these hierarchically structured assessments between sets of OPAL users to allow them to select potential partners. The main feature of the matrix visualisation is the ability for users to assess the context of a specific assessment as the visualisation not only reveals simple related statistics for the two users concerned, but also overlays summaries of related assessor and candidate evaluations as compact and ordered 'value bars' when the user examines information in the matrix. This enables the user to better decide whether a given assessment is in line with what would be expected from an assessor's and candidate's history, or whether it indicates a specifically localised interplay between the two users. Other features include a simple focus+context effect that can reveal the tree-like structure and details of assessments, and filtering assessments by their position in the matrix or by particular assessment attributes.