Descriptive statistics are reported in Table 1. Please note that the means and standard deviations reported for the within-person measures (lower part of the table) are based on aggregates per individual across T2 to T6.
Development of the Short-Version RRS
To establish the most suitable set of items we departed from the Dutch version of the RRS. To reiterate briefly, the criteria for scale development were to establish a brief measure that is suited for studies with repeated assessments, has acceptable psychometric properties, is in accordance with a standard definition of rumination, and captures distinguishable aspects of rumination (brooding and reflection).
We started with two separate measurement models for the two subscales of the RRS, reflection and brooding. For the reflection subscale, we selected those three items from the RRS as reported by Treynor et al. (2003) that do not have a reference to negative feelings (Table 2). To avoid confusion with the original reflection scale, we renamed the scale into reflective self-regulation. The three items were modelled as indicators of a latent reflection factor at the within- and between-person level using MCFA. All items had sufficient within-person variance, as indicated by the ICCs (reported in Table 2). The model fit of this multilevel one-factor model was good, RMSEA = <.001, CFI = 1.0, SRMRwithin = .001 and SRMRbetween = .004. The emerging factor loadings are presented in Table 2. Next, we estimated the reliability of the reflective self-regulation subscale (i.e., composite reliability / omega), the estimates being omegawithin = .71, omegabetween = .94.
For the brooding subscale, we started out with items from this subscale as reported by Treynor et al. (2003). The items were modelled as indicators of a latent brooding factor at the within- and between-person level using MCFA. None of the combinations of items (combinations of three to five items of the Treynor items) resulted in a reliable subscale of brooding at the within-person level (i.e., composite reliability was <.60). To nevertheless obtain a reliable within-person subscale for brooding, we switched from our confirmatory to an exploratory approach. Specifically, we used multilevel exploratory factor analysisFootnote 1 on a selection of twelve items from the RRS, with the goal to find relatively homogenous items as indicated by factor loadings. The selection of the twelve items was guided by a defining feature of rumination—a focus of thoughts on symptoms of distress (Nolen-Hoeksema et al. 2008). The emerging set of five items with the highest loadings on the brooding factor is presented in Table 2.
In a final step, these items were tested as indicators of brooding in a confirmatory way, again using MCFA. All items had sufficient within-person variance, as indicated by the ICCs (Table 2). The model fit of this MCFA was good, RMSEA = .04, CFI = .99, SRMRwithin = .03 and SRMRbetween = .03. The reliabilities of this set of itemsFootnote 2 were omegawithin = .67, and omegabetween = .94. Given the more negative content of this brooding subscale in comparison to that by Treynor et al. (2003), we call this factor depressive brooding.
Together, these analyses provided two subscales, depressive brooding and reflective self-regulation, with good model fit for the final measurement models.
Modelling the 2-Dimensional Structure of Brooding and Reflection
Next, we tested whether rumination as measured with the new depressive brooding and reflective self-regulation subscales is indeed a two-dimensional construct at the within- and the between-person level of analysis. We tested the model fit of a two-dimensional model, including the two subscales, again using MCFA. The result is presented in Fig. 1. The model fit was acceptable, RMSEA = .06, CFI = .94, SRMRwithin = .05 and SRMRbetween = .06, and the correlations between factors indicated commonality and divergence between the two latent dimensions, rwithin = .51, rbetween = .67. We compared this model to a model in which factor correlations were fixed to 1 (which would indicate indistinctness of the factors), using χ2 difference testing. The result suggested that both factors should be kept, and thus, the existence of two distinguishable subscales.
The results of the analyses of convergent validity at the within-person level are reported in Table 3. Given this study’s specific interest in the coefficients that are informative on convergent validity, we only present the Level-1 coefficients representing within-person associations. Moreover, we report the amount of variance that the predictor variables explain in brooding and reflection (i.e., the pseudo-R2 statistic).
The new depressive brooding subscale significantly co-varied with rumination as measured with the CERQ, with depressive symptoms, and with BDI-negative feelings. That is, occasions on which study participants had particularly high levels of depressive brooding were occasions on which they also had high levels of rumination (CERQ), depressive symptoms and BDI-negative feelings. The amount of variance in within-person depressive brooding that was explained by these predictors ranged between 25 and 27%.
The new reflective self-regulation subscale significantly co-varied with CERQ- rumination at the within-person level. Yet, the amount of variance that CERQ-rumination explained in within-person reflection is small (1%). Moreover, reflection was neither significantly associated with depressive symptoms nor with BDI-negative feelings at the within-person level. The amount of variance in within-person reflection that is explained by depressive symptoms and BDI-negative feelings is 9% in both cases.
The results for the analyses of convergent validity at the between-person level are reported in Table 4. All correlations between the new depressive brooding and reflective self-regulation subscale and the indicators of convergent validity were significant. In more detail, the correlations between the new depressive brooding subscale and the standard measures of rumination (i.e., the standard brooding subscale of the RRS; the rumination subscale of the CERQ) were .54 and .51, respectively. Moreover, the correlations between the new brooding subscale and depressive symptoms and BDI-negative feelings were .64 and .54, respectively. The size of the correlations of the brooding subscale and negative affect was .49.
The correlation between the reflective self-regulation subscale and the standard reflection subscale of the RRS was also high, r = .60. The correlations between this subscale and the other measures were moderate, with the range of the correlations being .24 to .33. The smallest correlations were found between reflection and the standard brooding subscale as well as with BDI-negative feelings.