Observed intra-cluster correlation coefficients in a cluster survey sample of patient encounters in general practice in Australia

Table 3 Associations between demographic and morbidity variables, measured as odds ratios, with design effect (Deff) and intra-cluster correlation coefficients (ICC) with standard errors (SE) for sample year April 1999 to March 2000 (N = 1,047 general practitioners): and ICC and SE for sample April 2002 to March 2003 (N = 1,008 GPs).

		1999–2000 (N = 1,047 GPs)			2002–2003 (1,008 GPs)
Outcome*	Predictor	Odds Ratio	Deff ^(a)	ICC (SE)	ICC (SE)
a) Demographic
Patient holds health care card	Female patient	1.07	2.2	.012 (.001)	.018 (.001)
	Age (years)	1.03	6.5	.056 (.003)	.073 (.003)
	Patient language^(b)	1.26	13.7	.128 (.005)	.114 (.005)
Patient language^(b)	Female patient	0.94	3.7	.028 (.002)	.024(.001)
	Age (years)	1.00	11.2	.104 (.004)	.098 (.004)
b) Morbidity Chapters
Cardiovascular	Female patient	0.90	1.3	.003 (.001)	.004 (.001)
	Age (years)	1.05	2.1	.011 (.001)	.017 (.001)
	Holds health care card	2.55	2.4	.014 (.001)	.018 (.001)
	Patient language^(b)	1.17	5.2	.042 (.002)	.034 (.002)
Respiratory	Female patient	.86	1.3	.003 (.001)	.003 (.001)
	Age (years)	.99	2.5	.015 (.001)	.022 (.001)
	Holds health care card	.89	2.1	.011 (.001)	.017 (.001)
	Patient language^(b)	1.17	2.9	.020 (.001)	.025 (.002)
Psychological	Female patient	1.13	2.2	.013 (.001)	.008 (.001)
	Age	1.01	3.3	.024 (.001)	.022 (.001)
	Holds health care card	1.89	2.4	.014 (.001)	.020 (.001)
	Patient language^(b)	.74	5.0	.040 (.002)	.026 (.002)
Endocrine/metabolic	Female patient	.95	1.6	.006 (.001)	.004 (.001)
	Age	1.03	2.1	.011 (.001)	.012 (.001)
	Holds health care card	1.63	2.4	.014 (.001)	.009 (.001)
	Patient language^(b)	1.58	3.3	.023 (.001)	.019 (.001)

* Each predictor is fitted alone, each line represents a separate model.
^(a)Average number of observations per cluster k = 100, except age (k = 99.2) and sex (k = 98.8).
^(b)Patient speaks a language other than English at home.

ISSN: 1471-2288