Spline

... you have enough points you could fit some sort of interpolating polynomial, but I don’t see how that would help you much. Maybe even Excel has a spline or interpolating function. A free-hand curve should do, I would think. There are times when you need to "fit a line" by least squares ...

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... samples from this file. The standards data are used to form a characteristic or standard curve which may be modeled using a three point cubic spline or a four parameter logistic-log function . The four parameters of the logistic function may be estimated using two methods: iteratively reweighted ...

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