Lin's Concordance Correlation Coefficient
Lin's concordance correlation coefficient measures how closely paired measurements fall on the 45-degree line of identity, combining precision (Pearson correlation) and accuracy (closeness of means and variances).
Lin의 일치상관계수는 짝지은 측정값이 45도 동일선에 얼마나 가까운지를 재며, 정밀도(피어슨 상관)와 정확도(평균·분산의 근접성)를 함께 반영합니다.
How well do blood pressure readings from a home device agree with readings taken by a nurse?
가정용 혈압계 측정값이 간호사가 잰 혈압과 얼마나 잘 일치하나요?
Lin's coefficient equals twice the covariance divided by the sum of the two variances plus the squared mean difference, so it falls below the Pearson correlation whenever the means or scales differ. It decomposes into precision times a bias-correction factor, and its confidence interval is obtained on the Fisher z scale.
When to use Lin's Concordance Correlation Coefficient
- Two methods or raters produce continuous scores for the same subjects
- Agreement, not just association, is the question
- A single summary of agreement is wanted alongside a Bland–Altman plot
When to use something else
- Ratings are categorical, where Cohen's or weighted kappa fits
- Several raters must be assessed together, where an intraclass correlation is more suitable
Assumptions and requirements
- Paired continuous measurements
- Approximately bivariate normal data for the confidence interval
- Independent subjects
What the analysis reports
- Concordance correlation with 95% CI
- Pearson correlation (precision)
- Bias-correction factor Cb (accuracy)
- Location and scale shift
How to report it
Concordance between the two methods was ρc = [value], 95% CI [[value], [value]] (N = [value]), with precision r = [value] and accuracy Cb = [value].
Related methods
Run Lin's Concordance Correlation Coefficient on Quorant
- Data you need
- a table (CSV or Excel) with item columns (e.g. questionnaire items)
- Price
- 150 credits for one analysis up to 10,000 rows (complexity level 1); larger or wider data costs more. Optional methodologist review: 900 credits.
- Checking
- Checked by property tests in every deployment
- Before you pay
- A free pre-analysis diagnosis checks your data and gives an exact quote; nothing is deducted until you approve it.