The association between positive and negative affect at the inter- and intra-individual level

- Associations may be different at the between- and within-subjects level.
- A random-effects approach can be used to estimate correlations at the two different levels.
- Large correlations were found between positive and negative affect at both levels.
- The discrepancy between the estimates was larger with more repeated observations available.

BackgroundIt is unclear to what extent positive affect (PA) and negative affect (NA) may co-occur across and within people. The present study aimed to find unbiased estimates of the between- and within-subjects association between PA and NA.Methods85 participants recorded their PA and NA daily by means of an electronic diary (mean 38 observations, range 2 to 56). A linear mixed-effects model was applied. The covariances between the random effects at the person- and measurement level were used to simultaneously estimate the between- and within-subjects correlation between PA and NA.ResultsThe within- and between-subjects correlation between PA and NA were large: r = −0.56 (95% CI −0.58 to −0.54) and r = −0.52 (95% CI −0.69 to −0.40), respectively. The difference between the correlations was not significant (Fisher Z = −0.56; P = 0.58). In participants who completed ≥ 80% of the measurements (n = 46), the within- and between-subjects correlation were r = −0.59 (95% CI −0.61 to −0.57) and r = −0.50 (95% CI −0.67 to −0.28), respectively (Z = −0.98; P = 0.33).ConclusionOur study suggests that the correlation between PA and NA is large, both at the within- and between-subjects level. The discrepancy between the two correlations as estimated by mixed-effects models may be larger if more repeated assessments are available.