A new dialog box is displayed in which you can select a categorical variable. Subgroups: click the Subgroups button if you want to identify subgroups in the scatter diagram and residuals plot.As an option, the Residuals can be plotted by rank number (see Passing & Bablok, 1983).

Residuals: a graph window with a residuals plot.Scatter diagram & regression line: a graph window with scatter diagram and regression line, including confidence interval for the regression line and identity line (x=y).Spearman rank correlation coefficient: select this option to include Spearman's rank correlation coefficient in the report.This is different from the traditional (least squares) method which measures residuals parallel to the y-axis. Calculate perpendicular residuals: select this option to calculate the residuals perpendicular to the regression line (see Passing & Bablok, 1983).Variable Y and Variable X: select the variables for the two techniques you want to compare.These confidence intervals are used to determine whether there is only a chance difference between B and 1 and between A and 0. The slope B and intercept A are calculated with their 95% confidence interval. The result does not depend on the assignment of the methods (or instruments) to X and Y. Passing-Bablok regression is a linear regression procedure with no special assumptions regarding the distribution of the samples and the measurement errors (Passing & Bablok, 1983).

Prism scatter plot calculator