Confirmatory and bi-factor analysis of the Short Form Health Survey 8 (SF-8) scale structure in a German general population sample

Table 2 Descriptive values and results of the scale analysis for the values of the SF-8 single items or the scale values

Scale/items	MD¹ n\|%	Number of response categories	M	SD	Skewness²	%Extreme³	r_iγ⁴	r_itc⁵ 1-DIM	r_itc⁵ 2-DIM^MOD	r_itc⁵ 3-DIM
Physical Health (PHS)								α = .923	α_PHS2 = .898	α_PHS3 = .892
PF—Physical Functioning	10\|0.4	5	81.20	23.81	−1.02	50.5	.134	.784	.806	.813
PR—Physical Role Functioning	9\|0.4	5	85.15	22.29	−1.41	59.7	.127	.803	.797	.828
BP—Bodily Pain	9\|0.4	6	80.16	23.80	−1.00	45.5	.120	.724	.741	.724

Overall Health (OHS)										α_OHS = .779
GH—General Heath Perception	6\|0.2	6	66.92	19.63	−0.16	11.8	.169	.709	.733	.638
VT—Vitality	10\|0.4	5	68.67	21.79	−0.44	17.4	.116	.680	.661	.638

Mental Health (MHS)									α_MHS = .854
SF—Social Functioning	10\|0.4	5	85.86	22.01	−1.38	63.1	.078	.709	.723
MH—Mental Well-Being	12\|0.5	5	86.76	21.61	−1.68	63.3	.098	.685	.749
RE—Emotional Role Functioning	33\|1.3	5	87.61	21.58	−1.81	67.5	.038^n.s	.727	.703

¹Number of missing data; ²standard error = .049; ³percentage of responses in the response category that does not indicate a health problem; ⁴correlation Item × weighting factor γ; ⁵corrected item-total correlation; n.s.: not significant; all other correlations p > .001

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