Generalizability Theory Applied to Daily Relationship Quality: Substantive and Statistical Directions.

Measuring daily romantic relationship quality is important for understanding conflict, support, and satisfaction processes in near real-time. Although there now exists a great deal of research on determinants and outcomes of daily relationship quality, these investigations often rely on several untested assumptions regarding sources of, and consistency in, variability. In this study, we tested the variance components for daily relationship quality, how consistent these measurements are, and whether they are impacted by individual differences in attachment security. Six daily, nonexperimental self-reports of relationship satisfaction and functioning (e.g., conflict) from 101 couples were analyzed using generalizability theory. Results demonstrate a large amount of residual in daily reports of relationship quality, yet significant portions of variance attributable to person- and day-level processes. Variance proportions also changed depending on the index of relationship functioning examined, and individual differences in attachment security moderated these results. Lastly, daily reports of relationship satisfaction are relatively stable when submitted to models using persons as the object of measurement. These findings have implications for planning and interpreting future diary and ecological momentary assessment/experience sampling method studies.