@CloudyGloudy That is true. So this is something akin to testing for one medical condition and correlating that with a test for a second one. The question still remains is this test sufficiently robust to say with any confidence that the test results are or are not similar?

I'd be happy to clarify. What part is unclear? Incidentally I tried a linear regression of R1 vs R2 on a few of the data sets I have been working on. I updated my original post.