The parameter path estimates examining the relation among the study variables are shown in Figure 1. The results demonstrated support for an Experiential Avoidance Model of NSSI such that increased emotional reactivity predicted more difficulties in emotion regulation (unstandardized coefficient = 0.06, standardized coefficient = .68, p<.001) which, in turn, predicted engagement in self-injury (unstandardized coefficient = 3.36, standardized coefficient = .34, p<.001). In terms of parental relationships, the results demonstrated that lower quality of relationship with parents predicted more difficulties in emotion regulation (unstandardized coefficient = .03, standardized coefficient = .24, p<.001), but not increased emotional reactivity (of note, the parental variables were transformed for normality such that higher scores on the IPPA indicated lower quality of relationships). Likewise, poor peer relationships predicted both more difficulties in emotion regulation (unstandardized coefficient = .01, standardized
coefficient = .1, p<.01) and greater emotional reactivity (unstandardized coefficient = 0.2, standardized coefficient = 0.12, p<.05).
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Figure 2. SEM Model of Intrapersonal and Interpersonal Predictors of NSSI (University)
.10* .68^ .65^ -.77^ .39^ .66^ .63^ .90^ .94^ .98^ .34^ .26^ .12* .05 -.07 .01 .63^ .85^ Mother Father Parental Reactivity Peers Regulation Frequency Methods NSSI Strat Goal Aware Clarity Accept Imp
Note. Strat = limited access to emotion regulation strategies; Accept = Non-acceptance of emotional
responses; Imp = impulse control difficulties; Clarity = lack of emotional clarity; Aware = lack of emotional awareness; Goal = difficulties engaging in goal-directed behavior
Note. Significance tests using robust statistics
*p<.05; **p<.01; ^p<.001
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Table 14. R-Squared Values for Latent Variable Indicators (University)
Strat Accept Imp Clarity Aware Goal Mother Father Freq Forms
R2 .81 .44 .60 .42 .15 .40 .72 .40 .89 .96
Note. Strat = limited access to emotion regulation strategies; Accept = Non-acceptance of emotional
responses; Imp = impulse control difficulties; Clarity = lack of emotional clarity; Aware = lack of emotional awareness; Goal = difficulties engaging in goal-directed behavior
As hypothesized, poorer parental relationships also predicted poorer peer relationships (unstandardized coefficient = 0.24, standardized coefficient = .26, p<.001). Contrary to the hypotheses, a direct relation between parental and peer variables with NSSI was not supported. Rather, the results demonstrated support for the hypothesized mediational relation among interpersonal and emotional variables. More specifically, the results suggest that negative parental and peer relationships exert their influence on NSSI via the mediating effects of difficulties in emotion regulation, rather than relationship quality in itself having a direct effect on these behaviours.
Estimates for the reliability of the measured variables as indicators of the latent variables are presented in Table 14. As demonstrated, both frequency of injury and number of methods used are reliable indicators of NSSI status. In terms of parental relationships, the results suggest that maternal relationship quality is a more reliable indicator of the latent factor, accounting for a greater proportion of variance in overall parental relationship quality. Finally, the subscales of the DERS also demonstrated variability in the proportion of variance that was accounted for by the underlying factor. Specifically, limited access to emotion regulation strategies accounted for the highest proportion of the underlying DERS factor, although lack of emotional awareness does not appear to be a reliable indicator of overall emotion regulation difficulties. The estimates of the remaining subscales ranged from .40 to .60.
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Post-hoc analyses were also run to examine modifications to the model that might improve the overall fit. No paths were removed based on the Wald Test as it only recommended the non-significant, but theoretically hypothesized, paths (e.g., the direct paths between
interpersonal variables and NSSI). The Lagrange Multiplier Test for adding parameters was also conducted with the suggested paths that would result in a statistically significant change to the CFI value being: paternal relationship to the DERS factor, maternal relationship to the DERS factor, and lack of emotional awareness to the latent parental factor. Although the fit would have been statistically improved with the addition of these paths, the model was not improved in a practical sense, with the CFI increasing from .93 to only .94. Therefore, no parameters were removed or added based on these tests.
Finally, although the results demonstrated that lack of emotional awareness was a significant indicator of the emotional regulation latent factor, it also demonstrated the lowest value for the path estimates (of the DERS indicators) and the r-squared value suggested that it is not a reliable indicator, with value of only 0.15. This result is consistent with that found by Heath and colleagues (2008) where lack of emotional awareness was the only subscale of the DERS that was not significantly different between individuals with a history of NSSI and individuals without. Likewise, Gratz and Roemer (2008) found that after controlling for demographic and other risk factors, the limited access to emotional regulation strategies and lack of emotional clarity subscales of the DERS remained significant predictors of NSSI, while lack of emotional awareness did not. Based on these findings, a modified full model was tested with the removal of lack of emotional awareness.
The overall chi-square test of the modified model was significant χ2 (37, N = 367) = 87.16, p<.001. The CFI value after the modification increased to 0.97 and the sRMR decreased
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to 0.04; the CFI using robust statistics was 0.98. The chi-square to degrees of freedom ratio was 2.36. The parameter estimates and significance values of the original full model presented in Figure 2 did not meaningfully change after the removal of the lack of emotional awareness subscale. Although a chi-square difference test could not be conducted as the models are non- nested, the AIC values were compared for descriptive information, with smaller values indicating a better fitting model. The AIC value for the full model was 101.35, and the AIC value for the modified model was 13.16, suggesting an improved model.