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Method

Chi-squared is calculated as Sum[(data-model)**2/variance], where variance is the variance of the data, unless the model array also has a VARIANCE component, in which case it is the sum of the model and data variances. i.e the program can be used to compare two datasets for compatibility. If the data have no error component then either Poisson or unit errors may be The number of degrees of freedom is taken to be the number of data points (i.e. model is assumed to be independent of data). Bad quality data points are excluded from the statistic, but the model array is assumed to be 100% good.



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