Using ecological socioeconomic position (SEP) measures to deal with sample bias introduced by incomplete individual-level measures: inequalities in breast cancer stage at diagnosis as an example

Table 1 Characteristics of included women depending on the availability of data on IDI

		respondents (IDI available (n = 1218))		non-respondents (missing data on IDI (n = 426))
		N	%	N	%	p-value*
age	less than 50	278	22.8	88	20.7	<0.001
	50 to 74	798	65.5	231	54.2
	75 or more	142	11.7	107	25.1
stage at diagnosis	Early	708	58.1	205	48.1	<0.001
stage at diagnosis	advanced	510	41.9	221	51.9	<0.001
EDI	q1 (least deprived)	307	25.2	97	22.8	0.361
	q2	300	24.6	99	23.2
	q3	265	21.8	89	20.9
	q4	202	16.6	76	17.8
	q5 (most deprived)	144	11.8	65	15.3

ISSN: 1471-2458