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Concordance correlation coefficient

Description

The concordance correlation coefficient ρc (Lin, 1989 & 2000) evaluates the degree to which pairs of observations fall on the 45° line through the origin. It contains a measurement of precision ρ and accuracy Cb:

     ρc = ρ Cb

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
  • Cb 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.

Required input

  • Select the variables of interest.

    If one or both variables needs Logarithmic transformation, select the corresponding option(s).

  • Optionally select a filter to include a subset of cases.

Results

The concordance correlation coefficient ρc (Lin, 1989 & 2000) evaluates the degree to which pairs of observations fall on the 45° line through the origin. It contains a measurement of precision ρ and accuracy Cb:

     ρc = ρ Cb

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
  • Cb 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):

Value of ρcStrength of agreement
< 0.90Poor
0.90 - 0.95Moderate
0.95 - 0.99Substantial
>0.99Almost perfect

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.

See also

Link

Go to Concordance correlation coefficient.