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

Background: It 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. Methods: 85 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. Results: The 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). Conclusion: Our 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. (C) 2016 Elsevier Ltd. All rights reserved.