Multidimensional fatigue inventory and post-polio syndrome – a Rasch analysis

Table 3 Fit of the MFI-20 to the Rasch model

	Item residual		Person residual		x ²		Unidimensionality
Analysis name	Mean	± SD	Mean	± SD	Value	p	PSI	test %	(LCI) %
MFI-20 20 items	0.50	2.17	−0.26	1.53	176.42	0.00	0.92	17.4	14.6
MFI-20 5 testlets	0.25	1.51	−0.31	1.02	22.80	0.09	0.86	4.4	1.6
General fatigue (GF)	0.14	1.06	−0.45	1.10	31.19	0.00	0.69	2.5	−0.5
GF 2 testlets	0.22	0.19	−0.41	0.69	4.01	0.68	0.77	1.5	−1.5
Physical fatigue (PF)	−0.03	1.81	−0.46	1.06	25.02	0.01	0.73	0.5	−2.5
PF 2 testlets	0.26	0.21	−0.57	0.90	7.35	0.29	0.80	3.1	0.0
Reduced activity (RA)	0.28	1.69	−0.50	1.17	24.63	0.02	0.75	3.8	0.8
RA 2 testlets	0.30	0.07	−0.48	0.73	3.39	0.76	0.82	5.1	2.2
Reduced motivation (RM)	−0.02	1.29	−0.38	1.16	25.62	0.01	0.30	1.5	−1.5
RM 2 testlets	0.18	0.42	−0.42	0.71	7.11	0.31	0.52	1.0	−2.0
Mental fatigue (MF)	0.26	1.42	−0.40	1.14	19.46	0.08	0.66	3.9	0.9
MF 2 testlets	0.33	0.02	−0.67	1.12	8.15	0.23	0.74	1.5	−1.5
*Ideal Values*	*0.0*	*<1.4* ^a	*0.0*	*<1.4*		*>0.05* ^b	*>0.85*		*(LCI <5%)*

^aMay be higher when unequal length testlets present b) Bonferroni adjusted.
PSI = Person Separation Index, SD = Standard Deviation, CI = Confidence Interval.

ISSN: 1477-7525