Concordance correlation coefficient

Command:

Statistics Agreement & responsiveness Concordance correlation coefficient

Description

The concordance correlation coefficient (Lin, 1989) evaluates the degree to which pairs of observations fall on the 45° line through the origin.

Required input

Select the variables for the two techniques you want to compare.

Results

The concordance correlation coefficient ρ_c contains a measurement of precision ρ and accuracy C_b:

$$\rho_c = \rho \space C_b$$

where

• ρ is the Pearson correlation coefficient, which measures how far each observation deviates from the best-fit line, and is a measure of precision, and
• C_b is a bias correction factor that measures how far the best-fit line deviates from the 45° line through the origin, and is a measure of accuracy.

Descriptive scale

McBride (2005) suggests the following descriptive scale for values of the concordance correlation coefficient (for continuous variables):

Literature

• Lin L.I-K (1989) A concordance correlation coefficient to evaluate reproducibility. Biometrics 45:255-268.
• Lin L.I-K (2000) A note on the concordance correlation coefficient. Biometrics 56:324-325.
• McBride GB (2005) A proposal for strength-of-agreement criteria for Lin's Concordance Correlation Coefficient. NIWA Client Report: HAM2005-062. (PDF)

See also

• Intraclass correlation coefficient
  
• Inter-rater agreement (kappa)
• Cronbach's alpha
• Accuracy and Precision

External links

• Concordance correlation coefficient on Wikipedia.