Fit function

The usual regressio or correlation analysis uses a straight line
relationship between the two variables
*Y* = *a*+*bX*.

The Climate Explorer fit routine can also fit other functions, such as the parabola

*Y* = *a*+*bX*(1+*cX*).

In this case the correlation indicates the correlation between the
fitted right-hand side and *Y* and is therefore always positive.

For correlations between two time series, a cubic fit (*Y* = *a*+*BX*+*cX²*+*dX³*) and a
straight line plus time derivative (*Y* =
*a*+*bX*+c*Y'*) are also available.

The option "phase diagram" does not perform a fit and connects all
(*X _{i},Y_{i}*) pairs by a line.