Indices of Agreement

Robert Gilmore Pontius, Clark University


This chapter examines seven indices that measure the agreement between two variables that show a phenomenon in the same units on an interval scale. Each index defines agreement by comparing the Observed Disagreement to a Baseline Disagreement, where each index has a distinct definition of Baseline Disagreement. This chapter uses the examples from Chap. 8 to illustrate characteristics of the indices. Mean Deviation, Mean Absolute Deviation, Correlation, and Slope have clearer and more helpful interpretations than the indices of agreement.