A program for the weighted linear least square regression of unbalanced responses arrays

A program is described to establish the calibration diagrams by weighted, linear, least square regression of unbalanced responses arrays. Whatever the confidence level. the number of analysed standards solutions and of their available replicates, the program allows i) testing for scedasticity, linearity, outliers and normality, ii) evaluating slope and intercept of the calibration function and their confidence interval and iii) evaluating an unknown concentration and its confidence interval by interpolation/extrapolation. In the case of negative results of the linearity test, the program structure allows a fast evaluation of data to be discarded to attempt entering the linear range. The program was validated by analysing responses arrays obtained by adding a Gaussian noise to known response/concentration functional relationships. The results of validation tests led to the implementation of an empirical but efficient way to correct regression results when certain experimental situations lead to unjustified over-weighting of some responses. The analysis of some real calibration datasets allows evaluating the versatility of the software.