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Re: [Phys-l] calibration




Aug 5, 2007, at 2:23 PM, Folkerts, Timothy J wrote:


Finding the prediction interval for a linear regression is a little more complicated than just finding the St Dev of the various points. It may be convenient to define the uncertainty of p as the standard deviation of such fluctuations, but it is not the standard practice. You should perhaps check a stats book for more info on the topic.

A quick run of the data through Minitab suggests that the +/-1 stdev prediction interval (68.3% confidence level) for r = 0.62 is p = 30.25 +/- 6.5. This is half again as large as the interval you list. The size of the prediction interval also changes across the range of the graph.

A couple minor points.
1) The resistivity of Cu is about 10^-8, not 10^+8.
2) I get 4.004, not 4.04 for stdev, but that could be round off error in the calculations or the original data.

Thanks Tim,
I will replace giga-ohms with nano-ohms today and will check in a statistics book later. A pedagogically good Internet reference would be appreciated (for calculating uncertainties from residuals).
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Ludwik Kowalski, a retired physicist
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