Over the last three decades, the Rubber Process Analyzer has evolved as the processability test instrument of choice for measuring and solving many rubber factory problems. Also a new ASTM reflective microscope method is also commonly used. Now there is a total of nine different RPA ASTM International methods that are routinely used by the rubber industry to measure quality of raw rubber, state-of-mix differences for rubber compounds, predictions of downstream processability differences, etc. Of course, there are comparative advantages and disadvantages for each of these RPA ASTM methods, depending on the quality differences of the raw rubber and quality differences among factory recipes, even among compounds that are used for the same purpose. This paper discusses the statistical comparative advantages found from the results of a new special laboratory study with specially mixed rubber compounds to compare the relative advantages of each of the existing ASTM methods which include the use of the RPA as well as the special reflective microscope.