Kendall's coefficients for Attribute Agreement Analysis

Find definitions and interpretation guidance for Kendall's coefficients.

Coef

Use Kendall's coefficient of concordance (Coef) to assess the association between appraisers when ratings are ordinal and you have 3 or more levels of ratings.

Kendall's coefficient accounts for the order of scores, but kappa statistics do not. For example, Kendall's coefficient accounts for the fact that the consequences of misclassifying a perfect item (rating = 5) as bad (rating = 1) are more serious than misclassifying the item as very good (rating = 4).

Interpretation

Kendall's coefficient of concordance can range from 0 to 1. The higher the value of Kendall's, the stronger the agreement.

For more information, see Kappa statistics and Kendall's coefficients.

Chi-Sq

The approximate chi-square statistic that is used to determine the p-value in a chi-square test.

DF

The degrees of freedom (DF) are used with the chi-square value to determine the p-value. DF = N–1.

P

The p-value is a probability that measures the evidence against the null hypothesis. Lower p-values provide stronger evidence against the null hypothesis.

Use the p-value for Kendall's coefficient of concordance to determine whether to reject or fail to reject the null hypothesis.
  • H0: The appraiser agreement is due to chance.
  • H1: The appraiser agreement is not due to chance.

Minitab uses the chi-square value to determine the p-value.

Interpretation

To determine whether ratings are associated, compare the p-value to the significance level. Usually, a significance level (denoted as α or alpha) of 0.05 works well. A significance level of 0.05 indicates that the risk of concluding that the ratings are associated–when, actually, they are not–is 5%.
P-value ≤ α: The appraiser agreement is not due to chance (Reject H0)
If the p-value is less than or equal to the significance level, you reject the null hypothesis and conclude that the appraiser ratings are associated with one another.
P-value > α: The appraiser agreement is due to chance (Fail to reject H0)
If the p-value is larger than the significance level, you fail to reject the null hypothesis because there is not enough evidence to conclude that the appraiser ratings are associated.
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