Decomposing variance in co-rumination using dyadic daily diary data
Co-rumination is the process of perseverating on problems, negative thoughts, or feelings with another person. Still unknown is how co-rumination unfolds within the daily lives of romantic couples. Using a variance decomposition procedure on data from a 14-day dyadic daily diary, we assess how much co-rumination varies over time and whether it is a couple- or individual-level process. Results revealed that within-person fluctuations in co-rumination contributed most (~33%) to the total variance and that these fluctuations could be reliably assessed using multi-item summary scores. Although time-invariant between-couple differences account significantly for the total variance (~14%) and can be reliably assessed, there is little within-couple agreement on the extent to which co-rumination fluctuates on a daily level. More research is needed to understand when and why perceptions of daily co-rumination diverge within couples, and how this informs theory on co-rumination and similar ostensibly dyadic constructs.