Alison Bobal and Jill Emery have published "Gathering the Needles: Evaluating the Impact of Gold Open Access Content with Traditional Subscription Journals" in Insights: the UKSG Journal.
Here's an excerpt:
Utilizing the Project COUNTER Release 4 JR1-GOA report, two librarians explore these data in comparison to journal package subscriptions represented via the JR1 reports. This paper outlines the methodology and study undertaken at the Portland State University Library and the University of Nebraska Medical Center Library using these reports for the first time. The initial outcomes of the study are provided in various Tables for 2014 and 2015. The intent of the study was to provide both institutions with a baseline from which to do further study. In addition, some ideas are given for how these reports can be used in vendor negotiations going forward.