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Re: cold resistors



How big is chi-squared for each fit and how much does the
probability of fit improve?
Regards,
Jack

Adam was by constitution and proclivity a scientist; I was the same, and
we loved to call ourselves by that great name...Our first memorable
scientific discovery was the law that water and like fluids run downhill,
not up.
Mark Twain, <Extract from Eve's Autobiography>

On Mon, 3 Jan 2000, John Denker wrote:

At 09:57 PM 1/2/00 -0800, John Mallinckrodt wrote:
I get a far better fit to all but the 100 degree point with
log(R) = 4.36/T - 0.5

which does at least agree with your observations 1) that fiddling with the
exponent can produce better results and 2) that the 100 degreee point may
be anomalous.

1) Your numbers look right; my previous numbers were off because I
inadvertently transposed the inputs to the curve-fitter. (A straight line
has the property that its inverse function isn't conspicuously
different. Duh.)

2) I agree that an exponent of -1 works better than -0.5, but I stand by my
assertion that -0.85 works better than either. The -1 value would be
consistent with "ordinary" thermal activation (Arrhenius law); other
values imply that something else is going on. Latest & greatest fit:

log(R) = 5.2392 T^(-0.85) - 0.7491

after dropping the 100K point.