threshold = pwGetChisqThreshold(dof, alpha) Determines the chi-square threshold corresponding to the specified degrees of freedom and significance threshold.
dof Degrees of freedom, e.g. number of data points (N) or
N - number of parameters (N - p).
alpha Significance threshold 0..1, e.g. 0.05 (default).
If the chi-square value of a fit is below the calculated chi-square threshold, the model can not be rejected as a wrong model. If the chi-square value is larger, the model can be rejected: Only in alpha*100 percent of the cases, the model produces the measured (or more extreme) data.