Development of the 8-Item Phlegm Pattern Questionnaire (PPQ-8) Using Rasch Analysis

Table 3

Differential item functioning results by gender and age.

Item	Gender				Age
	Male (logit)	Female (logit)	Chi-square value	value	Younger (logit)	Older (logit)	Chi-square value	value
Cough (Q1)	0.12	−0.10	4.753	0.029	<0.01	<0.01	1.631	0.202
Sputum (Q2)	0.39	−0.32	24.105	<0.001	0.14	−0.13	8.021	0.005
Feeling of foreign body (Q3)	0.19	−0.16	3.677	0.055	0.11	−0.11	4.595	0.032
Breath shortness (Q4)	0.06	−0.06	1.678	0.195	−0.03	0.03	0.006	0.937
Indigestion (Q5)	−0.06	0.05	1.502	0.220	0.15	−0.15	4.501	0.034
Stomach fullness (Q6)	−0.04	0.03	0.297	0.586	−0.03	0.03	0.070	0.790
Poor appetite (Q7)	−0.07	0.05	2.314	0.128	0.01	−0.01	0.031	0.861
Abdominal rumbling (Q8)	0.27	−0.23	8.709	0.003	0.21	−0.21	7.224	0.007
Sickness (Q9)	−0.02	0.02	0.620	0.431	0.10	−0.10	4.556	0.033
Head unclearness (Q10)	0.10	−0.08	2.587	0.108	0.09	−0.08	1.980	0.159
Headache (Q11)	−0.06	0.05	0.038	0.846	0.12	−0.12	4.209	0.040
Dizziness (Q12)	−0.12	0.10	0.122	0.727	0.07	−0.07	2.535	0.111
Tinnitus (Q13)	0.07	−0.06	0.148	0.701	−0.18	0.17	9.853	0.002
Palpitation (Q14)	−0.24	0.20	8.885	0.003	−0.15	0.14	5.061	0.025
Startled by faint noise (Q15)	−0.36	0.29	19.496	<0.001	−0.15	0.14	5.374	0.020
Chest discomfort (Q16)	−0.13	0.10	1.362	0.243	−0.09	0.09	2.642	0.104
Mucousy stool (Q17)	0.15	−0.13	4.981	0.026	0.93	−0.03	<0.001	0.999
Flank pain (Q18)	-0.01	0.00	0.071	0.790	−0.09	0.09	0.988	0.320
Joint pain (Q19)	−0.22	0.18	7.847	0.005	−0.40	0.38	21.922	<0.001
Limb heaviness (Q20)	−0.17	0.14	4.309	0.038	−0.09	0.09	2.550	0.110
Dark circle (Q21)	−0.01	0.01	1.003	0.317	0.32	−0.31	17.714	<0.001
Lumps (Q22)	0.08	−0.07	1.439	0.230	−0.09	0.08	3.284	0.070
Yellow face (Q23)	−0.19	0.16	8.885	0.003	−0.04	0.04	1.679	0.195
Itching (Q24)	0.29	−0.24	9.435	0.002	−0.08	0.08	3.955	0.047
Fatigue (Q25)	−0.04	0.04	0.840	0.360	0.09	−0.08	0.517	0.473

The values in bold indicate significant differences in logit values between gender and age.