Grafidy - Goodness of fit

A Goodness of Fit parameter is calculated for each data curve. The parameter gives an indication of how well the best-fit curve matches the collected data curve. This parameter is calculated from the ratio of the misfit parameter and the eddy current area parameter. The misfit parameter is the square of the point-by-point difference between the best-fit curve and the data. The eddy current area parameter is the sum of the square for each measured data point. A small Goodness of Fit value indicates a good fit (difference between the fit and data is small) and a large Goodness of Fit value indicates a poor fit.

The Goodness of Fit parameter is used in Auto mode as one mechanism to determine whether the component is calibrated and if another iteration is required. If the Goodness of Fit value is low, the tool will continue to iterate even if the peak value is below the target. If the Goodness of Fit value is large, the tool will stop iterating even if the peak value is greater than the target.