In order to relate reusability with economic impact, it is necessary to have a quantitative metric for the concept of reusability and a practical methodology to carry on an assessment. Although some other metric with extensive support are available (5 stars of Tim Berners-Lee), this metric lacks of a critical factor, which is the legal licensing of the released data. This factor is absolutely critical for professional reuse. Other metrics not specific of information reuse have also been analysed and some of their principles have been also assumed (Pipino et al, 2002) but with 16 dimensions (some of them subjective) it means these metrics are not really feasible to be implemented. Ren and Glissman (2012) proposed metric, although supposedly oriented to open data,considers dimensions which are not critical for professional re-user but for internal managers. (i.e. This metric consider Accessibility / Availability, understandability, completeness / correctness, timeliness, free of error and security dimensions). The legal aspect is again deprecated. As a consequence of the inability to assess properly the concept of reusability, MELODA metric has been evolved in this work. It is based on previous works of the author. MELODA is a metric that implements 6 out of the 8 principles of open government data (Lessing et al, 2007) but in a way in which datasets can be assessed individually and a singular mark can be assigned to everyone.
MELODA comprehends, in current version 2.5, just three dimensions of information, Legal, Access and Technological standards, and they are assessed against a standard with 5 structured levels each. Every level is weighted and overall impact is aggregated. The next three points describe those dimensions and the different levels set of each one.