You should take a class in applied statistics.
As long as the transponder remains in the same spot for a long time, calibration is irrelevant. Its comparative relationships and means that matter.
I’ll wait for the real scientists to verify the data ... and in the meantime, you can use the backyard-wannabe-scientists. You might even buy one yourself and put it in your backyard.
Let me know when the scientists issue a report on it and I’ll read that.