Estimating the Reliability of the Data The data from these experimen were anal using the statistical methods described in Chapters 5- 8. For each of the standard arsenic solutions and the deer samples, the average of the three absorbance measurements was calculated. The average absorbance for the replicates is a more reliable measure of he concentration of arsenic than a single measurement. Least squares analysis of the standard data (see Section 8D was used to find the best straigh ne among the points and to calculate the concentrations of the unknown sam ples along with their statistical uncertainties and confidence limits,