Table 3. Comparison of measurement invariance models between Wave 1 (n = 888) and Wave 2 (n = 966).

Invariance models	SCS					CSBC					CAS
	χ2	df	RMSEA [90% CI]	CFI	ΔCFI ΔRMSEA	χ2	df	RMSEA [90% CI]	CFI	ΔCFI ΔRMSEA	χ2	df	RMSEA [90% CI]	CFI	ΔCFI ΔRMSEA
Equal structure	19.808	4	0.065 [0.038, 0.095]	.993		125.509	22	.071 [.058, .084]	.964		27.844	4	.080 [.054, .11]	.981
Equal loadings	40.262	7	.072 [.051, .094]	.985	.008 .007	130.280	26	.066 [.055, .077]	.964	0 .005	44.282	7	.076 [.055, .098]	.971	.010 .004
Equal intercepts	95.810	10	.096 [.079, .114]	.960	.025 .024	342.959	30	.106 [.096, .116]	.892	.072 .040	197.431	10	.142 [.125, .160]	.852	.119 .066
Partially equal intercepts a	43.765b	9	.065 [.046, .084]	.984	.001 .007	135.786 c	28	.064 [.054, .076]	.963	.001 .002	47.220 d	8	.073 [.053, .093]	.969	.002 .003

Note. All models are compared to the model above them in the table, except ^a, which is compared to the model with equal loadings. Invariant intercepts: ^b Items 2 & 3, ^c Items 1, 4, 7 & 11, ^d Items 2. SCS = Short Cyberchondria Scale; CSBC = COVID-19 Safety Behaviour Checklist; CAS = COVID-19 Anxiety Scale; SB = Satorra-Bentler; RMSEA = root mean square error of approximation; CI = confidence interval; CFI = comparative fit index. The internal consistency of all scales, expressed by McDonald’s omega and Cronbach alpha coefficients, is presented in Table 4. For most scales, the reliability was lower on the second wave (i.e. Sample 2), especially for Protection Behaviour in the COVID-19 Safety Behaviour Checklist.