The weighted average is used to calculate the average of numerical values that have been assigned different weights.
2021.Īll rights reserved.In Excel, the weighted average is calculated by using the SUMPRODUCT function in the numerator and the SUM function in the denominator.
Plotting the Bland-Altman limits of agreement.Plotting a difference plot and estimating the average bias.Testing commutability of other materials.Estimating the bias between methods at a decision level.We recommend the use of correct methods such as Deming regression. In such cases the slope and intercept estimates have little bias, but hypothesis tests and confidence intervals are inaccurate due to an underestimation of the standard errors (Linnet, 1993). Typically, for methods that exhibit constant CV the higher values are less precise and so weights equal to 1 / X² are given to each observation.Īlthough the assumption that there is no error in the X variable is rarely the case in method comparison studies, ordinary and weighted linear regression are often used when the X method is a reference method. Weighted linear regression is similar to ordinary linear regression but weights each item to take account of the fact that some values have more measurement error than others. It, therefore, assumes that the X variable is measured without error. Ordinary linear regression finds the line of best fit by minimizing the sum of the vertical distances between the measured values and the regression line. Ordinary linear regression fits a line describing the relationship between two variables assuming the X variable is measured without error.
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