The D-Lib Magazine March/April 2014 published an article surveying metadata use in OpenDOAR repositories.

Brief Review

The creation of metadata for research and repository content is an essential part of the scholarly communication process and is necessary for the long-term access and preservation of our digital (and digitized) heritage. In spring 2014, authors from the University of Missouri conducted a nation-wide survey on metadata practices among United States-based OpenDOAR repositories.This study limited its scope to United States-based institutions and their repositories as listed on the OpenDOAR registry. Of the 328 OpenDOAR institutions listed in February 2014, we randomly selected 50 institutions for study. Examining the repository systems and current practices of metadata in these repositories, researchers collected and analyzed the responses of 23 repositories. Results from this survey include information about the creators of metadata, best practices and resources, and controlled vocabularies. Findings  informs libraries about the current state of repository and metadata choices in open repositories in the United States, especially as they pertain to overarching questions of interoperability.The usefulness of metadata is dependent on many factors, including system functionality, the encoding of metadata for machine manipulation, and the quality of the metadata. In this study we gathered information on systems used, metadata encoding schemes and elements that impact metadata quality, including the level of staff creating it and best practices resources in use, in an effort to describe metadata practices.

Read the full article here