The Harvard method was invented in 1992 by Dr James Thomas from Harvard and got a brief experimental verification.
Thomas JD, Flachskampf FA, Chen C, Guererro JL, Picard MH, Levine RA, Weyman AE. Isovolumic relaxation time varies predictably with its time constant and aortic and left atrial pressure: implications for the noninvasive of ventricular relaxation. Am Heart J. 1992;124:1305–1313. [PubMed] [Google Scholar]
Five years later, the method was clinically verified at Cleveland and the result was published in Circulation.
Scalia GM, Greenberg NL, McCarthy PM, Thomas JD,Vandervoort PM. Noninvasive assessment of the ventricular relaxation time constant in humans by Doppler echocardiography. Circulation. 1997;95:151–155. [PubMed] [Google Scholar]
Simple and clear, the formula has logic flaws: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6558577/pdf/jgc-16-05-429.pdf
To prove a flawed formula, the authors had to fabricate evidence. Nobody can get "meaningful" data by unintentional mistakes.
For more than two decades, quite a few projects have been based on the Harvard method of Tau. This is embarrassing.
Please get the above two "fake testimony" papers retracted.