We are receiving a lot of questions about relevant analyses in the Analyse-it Method Validation edition to help in evaluating new diagnostic tests in the fight against COVID-19. Below are some quick links that will help, but contact us if you have questions - we are working as normal.
Also see our latest blog post: Sensitivity/Specificity and The Importance of Predictive Values for a COVID-19 test
Regression of the differences on the true value describes the relationship between the methods.
Mean difference measures the constant relationship between the variables. An assumption is that the difference is not relative to magnitude across the measuring interval. If the differences are related to the magnitude, the relationship should be modeled by using relative differences or regressing the differences on the true value.