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What is the ICC in statistics?
In statistics, the intraclass correlation, or the intraclass correlation coefficient (ICC), is a descriptive statistic that can be used when quantitative measurements are made on units that are organized into groups. It describes how strongly units in the same group resemble each other.
What is a good ICC coefficient?
Under such conditions, we suggest that ICC values less than 0.5 are indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability, and values greater than 0.90 indicate excellent reliability.
What is a good ICC?
When to use partition coefficients and intraclass variance?
For example, if we make multiple observations on individual participants we partition outcome variance between individuals, and the residual variance. We might then want to know what proportion of the total variance is attributable to variation within-groups, or how much is found between-groups.
How to calculate the variance partition coefficient VPC?
This statistic is termed the variance partition coefficient VPC, or intraclass correlation. We calculate the VPC woth some simple arithmetic on the variance estimates from the lmer model. We can extract the variance estimates from the VarCorr function:
How is the interclass correlation coefficient ( ICC ) calculated?
The ICC is calculated by dividing the random effect variance, σ 2i, by the total variance, i.e. the sum of the random effect variance and the residual variance, σ 2ε. icc () calculates an adjusted and conditional ICC, which both take all sources of uncertainty (i.e. of all random effects) into account.
What does the ICC mean for variance decomposition?
For variance_decomposition (), a list with two values, the decomposed ICC as well as the credible intervals for this ICC. The ICC can be interpreted as “the proportion of the variance explained by the grouping structure in the population”.