Analyst Software Reference Guide - AB Sciex

Terms and ConceptsWeighting FactorsThe following table shows how the weighting factor (w in the equations below) is calculated foreach of the seven weighting types. See also Regression on page 34.Table 1-23 Weighting FactorsWeighting Type Weight (w)None Always 1.01 / x If |x| < 10 –5 then w = 10 5 , otherwise w = 1 / |x|. To place some additionalemphasis on lower-value points, use a weighting factor of 1/x.1 / x 2 If |x| < 10 –5 then w = 10 10 , otherwise w = 1 / x 2 . Use a weighting of 1/xsquared to provide a much higher emphasis on lower-value points.1 / y If |y| < 10 –8 then w = 10 8 , otherwise w = 1 / |y|. Use a weighting factor of1/y when calibrating by the area (y-axis) rather than by the concentration(x-axis), and you want to place some emphasis on lower-value points. Aweighting of 1/y is a variant of 1/x where y and x should be proportional toeach other.1 / y 2 If |y| < 10 –8 then w = 10 16 , otherwise w = 1 / y 2 . Use a weighting factor of1/y squared when calibrating by the area (y-axis) rather than by theconcentration (x-axis), and you want to place extra emphasis on lowervaluepoints. A weighting of 1/y 2 is a variant of 1/x 2 where y and x shouldbe proportional to each other.ln x If x < 0, then an error is generated, otherwise if x < 10 –5 then w = ln 10 5 ,otherwise w = |ln x|. Use the logarithm of x to place more weight onhigher value points.ln y If y < 0, then an error is generated, otherwise if y < 10 –8 then w = ln 10 8 ,otherwise w = |ln y|. Use the logarithm of y to place more weight onhigher value points. Use when calibrating by the area (y-axis) rather thanby the concentration (x-axis).52 Release Date: August 2011