"R-factors are calculated from what Verum director of research Sean Rife and his colleagues call golden citations, which reference manuscripts that directly replicate a particular study. (The vast majority of citations—about 95%—just mention other papers.) A paper’s R-factor is the number of confirmatory golden citations divided by the sum of confirmatory and refuting golden citations. The more reproducible a study is, the closer its R-factor is to 1."

http://physicstoday.scitation.org/do/10.1063/PT.6.2.20171004a/full/