Uncovering Indicators of the International Classification of Functioning, Disability, and Health from the 39-Item Parkinson's Disease Questionnaire

Table 3

Rasch item and fit statistics for the initial ICF scales of the PDQ-39^a.

	Item statistics^b			Fit statistics^b
Component	Item	Location^c	SE^c	Residual^d	Chi square^e,f	F-statistic^e,g
BF	17	−0.61	0.09	−1.65	𝟏𝟏.𝟑𝟎	𝟖.𝟔𝟗
	18	0.10	0.08	−1.08	2.70	2.12
	19	0.48	0.09	−0.15	2.39	1.44
	20	0.30	0.09	−0.44	3.11	1.60
	21	−0.27	0.09	−0.99	9.59	𝟓.𝟗𝟗
	22	−0.35	0.09	−0.83	7.24	4.47
	30	0.73	0.08	𝟐.𝟗𝟖	10.32	4.12
	31	−0.08	0.08	−0.68	4.42	2.82
	32	−0.10	0.08	𝟐.𝟓𝟐	2.22	1.19
	33	0.77	0.08	0.70	0.67	0.36
	37	0.01	0.07	2.18	3.80	1.69
	38	−0.64	0.08	1.92	3.62	1.87
	39	−0.33	0.08	2.25	7.76	3.19
AP	1	−0.64	0.09	−0.38	0.56	0.48
	2	−0.47	0.08	−2.06	4.65	4.05
	3	−0.54	0.07	−0.56	0.74	0.26
	4	−0.60	0.07	−0.09	1.11	0.12
	5	0.22	0.08	−0.88	5.21	3.56
	6	−0.18	0.08	−2.45	𝟏𝟐.𝟎𝟎	𝟏𝟎.𝟔𝟏
	7	−0.45	0.08	−𝟑.𝟗𝟔	𝟏𝟖.𝟑𝟒	𝟐𝟏.𝟕𝟗
	11	0.79	0.09	−2.27	10.54	𝟗.𝟖𝟒
	12	0.25	0.08	−2.04	5.52	4.67
	13	−0.42	0.08	0.35	4.75	2.47
	14	−0.73	0.09	2.01	𝟏𝟐.𝟔𝟒	𝟔.𝟐𝟔
	15	−0.01	0.08	0.92	2.82	1.72
	16	0.44	0.08	𝟑.𝟕𝟒	10.45	3.74
	24	0.48	0.09	𝟐.𝟗𝟏	9.05	3.55
	27	1.50	0.10	𝟑.𝟎𝟕	𝟑𝟏.𝟑𝟒	𝟏𝟐.𝟒𝟎
	35	0.36	0.08	2.27	2.62	1.23
E	8	−0.80	0.06	𝟑.𝟓𝟓	𝟑𝟒.𝟕𝟒	𝟏𝟑.𝟕𝟐
	23	−0.14	0.08	0.50	1.97	0.83
	25	−0.22	0.08	−0.82	𝟏𝟎.𝟗𝟎	𝟖.𝟐𝟐
	26	0.11	0.09	−0.30	𝟏𝟐.𝟗𝟒	𝟖.𝟐𝟓
	28	0.08	0.10	0.58	4.74	1.68
	29	0.42	0.09	−0.04	5.49	2.38
	36	0.55	0.10	−0.95	6.90	4.04

^aPerformed with the sample divided into three class intervals according to person locations on the measured construct.
^bRounded to two decimals.
^cExpressed in linear log-odds units (logits). Mean item location is zero with positive values representing more health problems.
^dResiduals summarize the deviation of observed from expected responses. Deviation from the recommended range from −2.5 to +2.5, indicating item misfit, are bold.
^eBonferroni corrected statistically significant deviations across class intervals, indicating item misfit, is bold.
^fChi-square values summarize the deviation of observed from expected responses across the three class intervals of people. Higher values represent larger deviations.
^gF-statistics from one-way ANOVAs of deviations from model expectation across the three class intervals of people.
ICF: International Classification of Functioning, Disability and Health; AP: Activity and Participation; BF: Body Functions and Structures; E: Environment; SE: standard error.