Table 3

Diagnostic group (pooled datasets) results of Rasch analysis

		Item fit residual		Person fit residual		χ² Interaction
Diagnostic group	Analysis	Mean	SD	Mean	SD	Value (df)	p Value	PSI	N	Proportion of significant t tests (95% CI)
Pooled AS	Analysis 1	0.563	2.959	−0.557	2.584	683.931 (351)	<0.001	0.972	661
Pooled AS	Analysis 2	0.314	0.905	−0.493	1.347	72.674 (63)	0.189	0.938	660	0.074 (0.058 to 0.092)
Pooled PsA	Analysis 1	0.957	3.096	−0.499	2.517	787.691 (351)	<0.001	0.975	780
Pooled PsA	Analysis 2	0.575	1.218	−0.445	1.279	70.460 (63)	0.242	0.944	777	0.071 (0.056 to 0.086)
Pooled SSc	Analysis 1	0.699	2.232	−0.532	2.634	527.415 (351)	<0.001	0.976	333
Pooled SSc	Analysis 2	0.664	1.270	−0.384	1.262	43.006 (35)	0.166	0.949	333	0.051 (0.026 to 0.074)
Pooled SLE	Analysis 1	0.560	2.559	−0.497	2.551	476.407 (234)	<0.001	0.969	360
Pooled SLE	Analysis 2	0.514	1.166	−0.421	1.298	39.817 (42)	0.567	0.932	358	0.051 (0.028 to 0.074)
Pooled FMS	Analysis 1	0.607	2.482	−0.251	1.972	450.441 (273)	<0.001	0.972	329
Pooled FMS	Analysis 2	0.378	0.986	−0.257	1.016	47.060 (42)	0.273	0.950	329	0.025 (0.001 to 0.048)
Pooled OA	Analysis 1	0.775	2.689	−0.701	3.022	709.905 (351)	<0.001	0.976	430
Pooled OA	Analysis 2	0.406	1.845	−0.434	1.273	99.906 (63)	0.002	0.950	429	Misfit
Expected values for a perfect model fit		0	1	0	1		>0.05	>0.70		Lower-bound CI <0.05

Analysis 1=Rasch analysis of the ENAT as a 39-item scale; Analysis 2=Rasch analysis of the ENAT as a 7-testlet scale.
AS, ankylosing spondylitis; DF, degrees of freedom; ENAT, educational needs assessment tool; FMS, fibromyalgia syndrome; OA, osteoarthritis; p, χ² probability (non-significant p, fit to the model); PsA, psoriatic arthritis; PSI, Person Separation Index; SLE, systemic lupus erythematosus; SSc, systemic sclerosis.