I notice that the examples always seem to talk about linear regressions, as in y=mx +c So how I understand this is that you get your sum of squared residuals and your parameters and you basically find the parameters which minimise the SSE. Would this mean, that you could essentially set up an excel spreadsheet that would let you use almost ANY expression using solver or VBA ? Even if you can't solve it algebraically you can get it close enough. Why do they focus on the situation which is least likely to be useful ? If something were the same as a straight line, why would you need to use such a complicated topic ?