In CHIME method it is best to have intercept of isochron on y-axis is closer to the origin. However, are there any maximum plus and minus values for the intercept of isochron in y-axis? Recently, some of my data sets show the maximum intercept as +0.05.
Hi Dadayakkarage, in my understanding the uncertainty values of the isochron intercepts in any isochron (not only in CHIME-produced ones; and also in, e.g., Ar-Ar and Rb/Sr dating) are usually determined by the number and (best-)fit of your data points along the line, expressed in terms of MSWD (Mean Square Weighted Deviation) and to be shown alongside the corresponding P (probability) value. Spread of data points (which can be expressed in %) also has an effect - imagine a small cloud of closely spaced data points somewhere on the isochron will generate much more uncertainty in at least one intercept compared to a nicely spread array of data points on the line; if the point cloud lies close to one of the x/y axes one intercept value can be calculated quite precisely). At least in Ar-Ar, any result with a P value smaller than 0.05 (=5%) should be considered non-robust and be treated with care. In my view, there is no "pre-defined" min./max. value for the errors on the intercepts - they all depend on your input data and internal statistics.
Dear Martin Schmieder, Thank you very much for your interesting answer. It is actually an another unavoidable interpretation which I have not taken account up to now. But now on I will.
I just added a quick illustration above - this should be applicable to all types of isochrons, regardless of the isotopic system.
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