The Oklahoma State Department of Education just published proposed rules for “Proficiency Based Promotion” which are open to comment until Feb. 5. They use proficiency based. They discuss how demonstrating proficiency of competencies can be used both for placing a student in the appropriate course/grade level and for issuing credit. At first, it seems like it is all about using exams, but as you read it in more detail it is actually pretty broad. (Added April 2016)
Evidence of Improved Achievement, Attainment, or Cost-Effectiveness: No information at this time (June 2014)