The fourth edition of the Open Data Barometer is based upon three kinds of data:

• A peer reviewed expert survey carried out between May and September 2016 with a range of questions about open data contexts, policy, implementation and impacts and a detailed assessment completed for 15 kinds of data in each country, which touched on issues of data availability, format, license, timeliness and discoverability.
• A government self assessment through a simplified version of the survey carried out between May and July 2016 with the same range of context, implementation and impact questions, provided an additional source of information.
• Secondary data selected to complement our expert survey data. This is used in the readiness section of the Barometer, and is taken from the World Economic Forum, World Bank, United Nations e-Government Survey and Freedom House.

The fourth edition of the Barometer repeats the analysis from previous editions, with the following modifications and methodological revisions:

• Completing the adaptation of the questionnaire to measure performance against the Open Data Charter principles This process was initiated in the previous edition of the Barometer on the basis of early drafts of the Charter.
• Adapting the implementation checklist to the new criteria defined by the updated open definition v2.1.
• Modifying the definition of some previously existing datasets [D2, D7 and D8]. (All of the definitions modified are for datasets that form part of the global anti-corruption open data infrastructure promoted by the Anti Corruption Open Up Guide.

Overall, however, we have sought to maintain consistency with questions used in
previous editions. Wider methodological revisions will continue to be explored in future editions as we continue to advance our measurement methods as part of our work in the Open Data Charter measurement and accountability working group.

The respective time periods under study for each completed ODB edition so far were:

• 4th edition: the 12-month period from July 2015 to June 2016.
• 3rd edition: the 12-month period from July 2014 to June 2015.
• 2nd edition: the 12-month period from July 2013 to June 2014.
• 1st edition: the 12-month period from July 2012 to June 2013.

The processing dates were:

• 4th edition: between August and December 2016
• 3rd edition: between July and October 2015.
• 2nd edition: between June and September 2014.
• 1st edition: between July and October 2013.

And the publication dates:

• 4th edition: May 2017.
• 3rd edition: April 2016.
• 2nd edition: January 2015.
• 1st edition: October 2013.

You can read more about the methodology and research process and method in the detailed methodology description (PDF version) and the research handbook (PDF version). Feel free to provide feedback by commenting on the online versions.

Historical and comparable consolidated data for all four editions of the Barometer is available on the Open Data Barometer website.