1. A method for determining the linearity of data points comprising the steps of: ascertaining an actual concentration (Y) of a sample of an analyte; measuring the sample to generate a result (X); computing a value of Z from the following formula: Z = ∑ i = 1 N X i 2 ( X i - X _ ) 2 ∑ i = 1 N X i ( X i - X _ ) computing a new variable (X−Z) 2 from each value of X; regressing X and (X−Z) 2 against Y to generate coefficients having values; evaluating the values of the coefficients of X and (X−Z) 2 , to determine if the linear term exceeds a threshold value to determine if nonlinearity exists.