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.