Table 3. Relationship between classification of socio-economic position and questionnaire delivery mode for each socio-economic domain.

	% in each SEP category				p-value	OR [95% CI]7
Socio-economic position (SEP)	IAQ1	SAQ2	AudioSAQ3	ACASI4		IAQ1	SAQ2		AudioSAQ3		ACASI4
Asset wealth score (n):	360	360	371	375		1.00	0.73 [0.56–0.95]		0.94 [0.72–1.23]		0.84 [0.64–1.09]
SEP 1 (Poorest - score 0.0–0.46)	35.0	43.6	38.8	43.7
SEP 2 (Score 0.47–0.62)	35.8	32.8	30.7	25.6
SEP 3 (Score 0.63–1.0)	29.2	23.6	30.5	30.7	p = 0.016 5
Mean score [SD]	0.55 [0.17]	0.52 [0.21]	0.55 [0.20]	0.54 [0.21]	p = 0.218 6
Ability to afford essential items (n):	364	368	376	375		1.00	0.53 [0.40–0.69]		0.68 [0.52–0.88]		0.68 [0.52–0.89]
SEP 1 (Poorest - score 0.0–0.43)	33.5	50.3	43.4	45.3
SEP 2 (Score 0.44–0.71]	36.0	29.9	33.5	28.8
SEP 3 (Score 0.72–1.00)	30.5	19.8	23.1	25.9	p<0.001 5
Mean score [SD]	0.60 [0.28]	0.49 [0.30]	0.53 [0.29]	0.53 [0.30]	p<0.001 6
Food sufficiency (n):	363	359	368	375
Insufficient food	35.0	50.1	48.1	46.9	p<0.001 5	1.00	1.87 [1.39–2.52]		1.72 [1.28–2.32]		1.64 [1.22–2.21]

¹IAQ = Interviewer administered questionnaire;

²SAQ = Self-administered questionnaire;

³AudioSAQ = Audio self-administered questionnaire;

⁴ACASI = Audio-computer assisted self-interview.

⁵Chi-square test;

⁶Oneway analysis of variance F-test;

⁷Crude odds ratio calculated using ordinal logistic regression for asset wealth and essential item SEP scores.