The effectiveness of a multi-source fusion process for decision making highly depends on the quality of information that is received and processed by the fusion system. This paper summarizes the existing quantitative analyses of different aspects of information quality in multi-source fusion environments. The summary includes definitions of four main aspects of information, namely, uncertainty, reliability, completeness and relevance. The quantitative assessment of quality of the information can facilitate evaluating how well the product of the fusion process represents the reality, hence contribute to improved decision making.