Analytical challenges of testing hypotheses of agreement and discrepancy: Comment on Campione-Barr, Lindell, and Giron (2020).

Researchers are often inclined to test agreement or discrepancy hypotheses using difference scores. This commentary explains 2 mathematical-statistical principles underlying associations with difference scores and 2 conceptual-interpretation problems that make difference scores inappropriate for testing such hypotheses. The commentary provides examples of valid and invalid interpretations of difference score associations in reference to...