Table 2.

Overview of Dimensionality Assessment Results.

Measure	CFA	EGA	Bifactor indices	Unidimensionality conclusion	Reliability
BPNSFS-A	L1	Two factors	ECV=.65, PUC=.53	−	α = .71 ω = .74
TEIQue-ASF-ER	L3	Two factors	ECV=.45, PUC=.60 a	−	α = .63 ω = .64
M&MF-I	DCFA: L2/L3 DWLS: CFI=.985, RMSEA=.095, SRMR=.06	Unidimensional	NA	+	α = .88 ω = .88
EPOCH-O	L0	Unidimensional	NA	+	α = .81 ω = .81
PANAS-C-PA	L0/L1	Unidimensional	NA	+	α = .92 ω = .92
SWEMWBS	L0	Unidimensional	NA	+	α = .86 ω = .86
RSS	L1	Unidimensional	NA	+	α = .91 ω = .91
PSS-4 b	ML fit: CFI=.571, RMSEA=.321, SRMR=.157 c	Two factors	ECV=.24, PUC=.67	−	α = .57 ω = .61

Note. CFA = confirmatory factor analysis; EGA = exploratory graph analysis; BPNSFS-A = Basic Psychological Need Satisfaction and Frustration Scale; ECV = explained common variance; PUC = percentage of uncontaminated correlations; M&MF-I = Me and My Feelings scale; DWLS = diagonally weighted least squares; DCFA = dynamic confirmatory factor anlaysis; CFI = comparative fit index; RMSEA = root mean square error of approximation; SRMR = standardized root mean square residual; TEIQue-ASF-ER = Trait Emotional Intelligence Questionnaire Adolescent Short Form; EPOCH-O = Engagement Perseverance Optimism Connectedness Happiness; PANAS-C-PA = PANAS-C positive affect subscale; SWEMWBS = Short Warwick Edinburgh Mental Well-being Scale; RSS = Rosenberg Self-Esteem Scale; PSS-4 = Perceived Stress Scale; L0 = no misspecification; L1 = Level-one misspecification; L2 = Level-two misspecification; L3 = Level-three misspecification.

^aA six-item bifactor model with three items per specific factor is not identified, so one lambda estimate from an unidentified run was used to identify the model as recommended (Muthén & Muthén, 2021). ^b For both the unidimensional and bifactor PSS-4 models, a Heywood case (negative residual variance) was found for the second item. This was fixed to 0. ^c Serious problems with the unidimensional model for PSS-4 meant further testing was not appropriate or possible.