The Jingle and the Jangle in Eudaemonic Wellbeing: Relatedness Converges for Self-Determination Theory and Ryff's Scales, but Autonomy Does Not

<p>Ryff's Psychological Wellbeing scales and the Basic Psychological Need Satisfaction and Frustration Scale (BPNSFS) are two of the most widely used instruments in eudaemonic wellbeing research, yet their measurement literatures are separate. Researchers routinely treat same-named scales as interchangeable and differently named scales as distinct, yet neither assumption has been tested. We tested two classic measurement fallacies across the instruments in a United Kingdom Prolific sample (N = 749). The jingle candidate was the pair of identically named Autonomy scales. The jangle candidate was Ryff's Positive Relations with Others and BPNSFS Relatedness, which carry different names. Latent correlations from confirmatory models with within-scale wording residuals showed a sharp asymmetry: the relatedness pair converged (r = .93), while the autonomy pair did not (r = .62). Self-Determination Theory Autonomy correlated more strongly with the relatedness measures than with Ryff Autonomy, a discriminant validity violation that holds regardless of how shared method variance is interpreted. Bias-corrected sensitivity estimates lowered the autonomy convergence further (r = .20). The two relatedness measures can be treated as largely interchangeable indicators of a common construct. The two autonomy measures cannot, and findings obtained with one cannot be assumed to generalize to the other.</p>