The Global Open Data Index is an annual effort to measure the state of open government data around the world. The crowdsourced survey is designed to assess the openness of specific government datasets according to the Open Definition.
Through this initiative Global Open Data Index wants to provide a civil society audit of how governments actually publish data - with input and review from citizens and organisations around the world.
Open data measurement is still new and experimental field. The Global Open Data Index as well makes changes each year in order to improve the quality of the final benchmarking.