Table 3.

Scale reliability and scores

Scale	# items	n	Cronbach's αa	Average inter-item correlation (IIC)b	Mean score (SD)
MFIS
Total score	21	158	0.94	0.41	33.89 (14.31)
Physical	9	158	0.90	0.51	19.34 (7.35)
Cognitive	10	158	0.93	0.57	10.65 (7.43)
Psychological	2	158	Too few items	Too few items	3.90 (2.17)
MFI
Total score	20	161	0.90	0.31	58.9 (14.00)
General fatigue	4	160	0.72	0.39	14.1 (3.35)
Physical fatigue	4	161	0.72	0.39	14.5 (3.60)
Reduced activity	4	161	0.82	0.53	11.34 (4.08)
Reduced motivation	4	161	0.62	0.29	9.94 (3.42)
Mental fatigue	4	161	0.85	0.58	8.89 (3.90)
FSS
Total score	9	145	0.92	0.57	4.8 (1.4)
PedsQL MF
Total score	18	150	0.91	0.37	60.31 (16.41)
General fatigue	6	150	0.87	0.53	48.91 (19.57)
Sleep/rest	6	149	0.77	0.36	59.48 (18.99)
Cognitive fatigue	6	150	0.94	0.74	72.81 (21.64)
SMA-HI
Fatigue	6	142	Values not calculated due to missing subscale items		56.95 (24.72)
Sleep	4	142			29.75 (26.42)

^aThreshold of acceptability for Cronbach's α > 0.7

^bRange of acceptability for IIC: 0.15–0.50