Data handling and interpretation in Method Comparisons

An example of data handling and interpretation in method comparison studies

The example is meant to be viewed in conjunction with the article “Assessment of Bias with Emphasis on Method Comparison” that appeared in the Clinical Biochemist Reviews 2008; 29: 121-6. It provides numerical comparison data for two glucose methods, one an existing (or reference) method and the other a new (or candidate) method, and describes how they might be analysed to decide whether the candidate method is fit for purpose.

The data are presented in a Microsoft Excel spreadsheet format under several tabs best viewed in the order given:

Data – representative comparison data and scatter plot

Difference – calculation and presentation of the difference plot

log Difference – log transformation of the data and calculation of a log difference plot

Statistics of log Difference – calculation of error and limits of error

Regression – least squares presentation with limits on slope and intercept

Summary – comparison with acceptable bias of statistical data calculated here, and for Deming and Passing-Bablok models 

No. 7 Bias Data FINAL (R. Johnson)