Longitudinal measurement invariance of the Working Alliance Inventory - Short form across coaching sessions

BMC Psychology

Table 4 Fit indices for multigroup confirmatory factor analysis of the 12-item WAI-S, three-factor model, across time (N = 490)

Three-factor model	χ^2d	df	χ²/df	RMSEA [90% CI]	CFI	TLI	SRMR	ΔCFI
Model^a
T1	219*	51	4.29	0.089 [0.077; 0.102]**	0.958**	0.945**	0.043**
T2	277*	51	4.46	0.091 [0.079; 0.103]**	0.952**	0.938**	0.040**
Configural	446*	102	4.38	0.090 [0.082; 0.099]**	0.955**	0.942**	0.041**
Metric	470*	111	4.23	0.088 [0.080; 0.096]**	0.954**	0.945**	0.049**	− 0.001
Scalar	515*	120	4.29	0.088 [0.080; 0.096]**	0.950**	0.945**	0.051**	− 0.004
Partial scalar	486*	118	4.12	0.086 [0.078; 0.094]**	0.953**	0.947**	0.050**	− 0.001
Model^b
T1	229*	60	3.81	0.082 [0.071; 0.094]**	0.958**	0.945**	0.040**
T2	234*	60	3.90	0.084 [0.073; 0.095]**	0.952**	0.938**	0.038**
Configural	462*	120	3.85	0.083 [0.075; 0.091]**	0.955**	0.942**	0.039**
Metric	485*	129	3.76	0.081 [0.074; 0.089]**	0.954**	0.944**	0.046**	− 0.001
Scalar	530*	138	3.84	0.082 [0.075; 0.090]**	0.950**	0.943**	0.049**	− 0.004
Partial scalar	501*	136	3.69	0.080 [0.072; 0.087]**	0.953**	0.946**	0.048**	− 0.001
Model^c
T1	249*	69	3.61	0.079 [0.068; 0.090]**	0.956**	0.942**	0.040**
T2	250*	69	3.63	0.080 [0.069; 0.090]**	0.951**	0.936**	0.038**
Configural	499*	138	3.62	0.079 [0.072; 0.087]**	0.954**	0.939**	0.039**	− 0.001
Metric	522*	147	3.55	0.078 [0.071; 0.085]**	0.952**	0.941**	0.045**	− 0.004
Scalar	566*	156	3.63	0.079 [0.072; 0.086]**	0.948**	0.940**	0.047**	− 0.001
Partial scalar	538*	154	3.49	0.077 [0.070; 0.084]**	0.951**	0.943**	0.046**

^aNo covariates; ^bCovariate = number of sessions; ^cCovariates: number of sessions and life satisfaction; ^dRounded at nearest integer; df = degrees of freedom; RMSEA = Robust root mean square error of approximation; CI = confidence interval; CFI = Robust comparative fit index; TLI = Robust Tucker-Lewis index; SRMR = standardized root mean residual
*p < 0.001; ^**Meeting threshold criteria: RMSEA/SRMR \(<\) .10, CFI/TLI \(>\) .90

ISSN: 2050-7283