Hi all,

I have data for a standard curve, which is linear from the origin over the majority of its length, and certainly over the length which contains the readings I want to take. At higher x-axis values, it tails off to an asymptote. Is there any way to use Excel or SPSS to interpolate/extrapolate my readings off this standard curve, remembering that my readings are in the linear part of the curve? Excel seems to take the higher points into account too much, giving results which are clearly incorrect.

Can anyone help?

Thanks! :-)