Evaluating the psychometric properties of the fatigue severity scale using item response theory

BMC Psychology

Table 2 Descriptive statistics

	Mean^a	SD	Skewness	Kurtosis	Cronbach’s alpha	ICC^b	95% CI lower	95% CI higher
MFI	55.73	12.75	-0.07	0.09	0.91	0.85^***	0.79	0.89
General fatigue	11.95	3.36	-0.03	-0.17	0.80	0.79^***	0.72	0.85
Physical fatigue	10.93	3.35	0.10	-0.11	0.80	0.79^***	0.72	0.85
Reduced activation	10.70	3.17	0.23	-0.02	0.69	0.76^***	0.68	0.83
Reduced motivation	11.06	2.81	-0.07	-0.02	0.53	0.74^***	0.65	0.81
Mental fatigue	11.10	2.79	0.04	0.54	0.66	0.71^***	0.61	0.79
FSS (Original)	3.52	1.30	0.20	-0.20	0.93	0.62^***	0.50	0.71
FSS (IRT)	3.22	1.31	0.10	-0.74	0.94	0.59^***	0.46	0.69
PHQ-9	4.75	5.21	1.71	3.56	0.91	0.83^***	0.77	0.88

Note. N = 692. 95% CI: 95% confidence interval, FSS: Fatigue Severity Scale, FSS (IRT): Fatigue Severity Scale (Item Response Theory), ICC: Intraclass correlation, MFI: Multidimensional Fatigue Inventory, PHQ-9: Patient Health Questionnaire-9, SD: Standard deviation
^a participants who responded to the first survey (N = 692)
^b participants who responded to both surveys and had their longitudinal data analyzed (n = 125)
^***p < .001

ISSN: 2050-7283