Table 3:

Known-group validity for PF10a using Cohen’s d effect size

	Age				Clinical disease activity
	<50 years	≥65 years			CDAI ≤10	CDAI >22
	N	N	Difference in mean PF10a	Cohen’s d	N	N	Difference in mean PF10a	Cohen’s d
Language
English	176	155	2.5*	0.24*	263	113	13.3*	1.44*
Spanish	9	18	6.6	0.69	18	13	11.6*	1.21*
Chinese	3	26	4.2	0.44	11	9	10.9*	0.95*
Insurance
Private	131	12	6.1*	0.64*	140	50	16.5*	2.15*
Medicare	22	184	−6.0*	−0.59*	131	55	9.9*	1.04*
Medicaid	35	3	−8.6	−1.00	21	30	9.6*	1.06*
Race/Ethnicity
White	94	94	2.3	0.23	161	54	13.3*	1.49*
African American	6	16	0.8	0.07	15	10	9.9*	0.96*
Hispanic	12	3	0.9	0.09	13	6	5.3	0.48
Asian	28	50	6.6*	0.64*	47	28	13.6*	1.37*
Other	48	36	3.8	0.36	56	37	13.7*	1.50*

Data source: Cross-sectional sample (N=595)

CDAI: Clinical disease activity index; PF10a: Physical function short-form 10a

Difference in mean PF10a score is the difference between mean PF10a among those <50 years compared to those ≥65 years or among those with CDAI ≤10 compared to those with CDAI >22; Cohen’s d is the difference in mean scores divided by the pooled standard deviation; Effect size (Cohen’s d) values are categorized as small (<0.5), medium (0.5-0.8), or large (>0.8).

^*P<0.05 using Student’s t-test; for Cohen’s d, 95% confidence intervals do not cross 0