This report for the OECD was done in 2009 but only recently released. It is available here:http://www.oecd.org/dataoecd/31/53/46560184.pdf
The Executive summary says:
"The open government agenda has gained momentum over the past decade. It is now widely acknowledged that greater openness benefits not only citizens but also government itself, by prompting better record management, making decisions and services more efficient and, at best, serving as a safeguard against misgovernment and corruption.
The purpose of this paper is to introduce new indicators for measuring government openness. Existing open government indicators tend to focus either on the presence of key laws and institutions, or on citizens’ perceptions of government performance. Neither option provides a full picture of comparative openness: the former gives little insight into the scope of the laws and institutions measured and the latter does not provide a quantitative picture of actual activities.
The indicators proposed in this paper are intended to fill this gap. They seek to complement, rather than replace, the existing data sets used for measuring government openness today. It is hoped that by improving the ways in which we assess open government, this project will contribute to a better understanding of what open government means in practice, which in turn will lead to improvements"