# Is there a table to interpret "how good" was the Kendall's coefficient of concordance (W)

As it is known, Kendall's coefficient of concordance (W) indicates the degree of association of ordinal assessments made by multiple appraisers when assessing the same samples.

Kendall's coefficient values can range from 0 to 1. The higher the value of Kendall's, the stronger the association. Usually Kendall's coefficients of 0.9 or higher are considered very good. A high or significant Kendall's coefficient means that the appraisers are applying essentially the same standard when assessing the samples.

Kappa, another statistic, measures the degree of agreement of the nominal or ordinal assessments made by multiple appraisers when assessing the same samples. Kappa values range from -1 to +1. The higher the value of kappa, the stronger the agreement. Not everyone would agree about whether, e.g., 0.57 constitutes “good” agreement.

Here is one possible interpretation of Kappa (1).

Poor agreement = Less than 0.20
Fair agreement = 0.21 to 0.40
Moderate agreement = 0.41 to 0.60
Good agreement = 0.61 to 0.80
Very good agreement = 0.81 to 1.00

It turns out that, using this scale, a kappa of 0.57 is in the “moderate” agreement range between two observers.

My question is: similar to Kappa, is there some "scientifically recognized" table to help visualize/interpret Kendall's W?

References

(1) Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159-74.