# Method comparison / Agreement

Method comparison measures the closeness of agreement between the measured values of two methods.

Note: The term method is used as a generic term and can include different measurement procedures, measurement systems, laboratories, or any other variable that you want to if there are differences between measurements.

**Correlation coefficient**

A correlation coefficient measures the association between two methods.**Scatter plot**

A scatter plot shows the relationship between two methods.**Fit Y on X**

Regression of Y on X describes the linear relationship between the methods.**Linearity**

Linearity is the assumption that the relationship between the methods is linear.**Residual plot**

A residual plot shows the difference between the measured values and the predicted values against the true values.**Average bias**

Bias is a measure of a systematic measurement error, the component of measurement error that remains constant in replicate measurements on the same item. When measuring a method against a reference method using many items the average bias is an estimate of bias that is averaged over all the items.**Difference plot (Bland-Altman plot)**

A difference plot shows the differences in measurements between two methods, and any relationship between the differences and true values.**Fit differences**

Regression of the differences on the true value describes the relationship between the methods.**Limits of agreement (LoA)**

Limits of agreement estimate the interval within which a proportion of the differences between measurements lie.**Mountain plot (folded CDF plot)**

A mountain plot shows the distribution of the differences between two methods. It is a complementary plot to the difference plot.**Agreement measures for binary and semi-quantitative data**

Agreement measures summarize the similarity of the results of two binary or semi-quantitative methods.**Agreement plot**

An agreement plot shows the agreement between two binary or semi-quantitative methods.

- What is Analyse-it?
- What's new?
- Administrator's Guide
- User's Guide
- Statistical Reference Guide
- Distribution
- Compare groups
- Compare pairs
- Contingency tables
- Correlation and association
- Principal component analysis (PCA)
- Factor analysis (FA)
- Item reliability
- Fit model
- Method comparison / Agreement
- Correlation coefficient
- Scatter plot
- Fit Y on X
- Fitting ordinary linear regression
- Fitting Deming regression
- Fitting Passing-Bablok regression
- Linearity
- Residual plot
- Checking the assumptions of the fit
- Average bias
- Estimating the bias between methods at a decision level
- Testing commutability of other materials
- Difference plot (Bland-Altman plot)
- Fit differences
- Plotting a difference plot and estimating the average bias
- Limits of agreement (LoA)
- Plotting the Bland-Altman limits of agreement
- Mountain plot (folded CDF plot)
- Plotting a mountain plot
- Partitioning and reducing the measuring interval
- Agreement measures for binary and semi-quantitative data
- Chance corrected agreement measures for binary and semi-quantitative data
- Agreement plot
- Estimating agreement between two binary or semi-quantitative methods
- Study design
- Study design for qualitative methods
- Measurement systems analysis (MSA)
- Reference interval
- Diagnostic performance
- Survival/Reliability
- Control charts
- Process capability
- Pareto analysis
- Study Designs
- Bibliography

Version 6.15

Published 18-Apr-2023