Just a second afterthought.

The measured impedance of a 2-terminal device tells you next to
nothing about it. It certainly does not tell you the Q.

To find anything useful about it, it is necessary to shift frequency
and make a SECOND measurement.

So we return, yet again, to a pair of independent measurements or
calculations in order to obtain a ratio.

A ratio has two degrees of freedom. I just love that phrase. I/ve been
waiting for years just to mention it.
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Reg.