Table 1.

Representativeness of the study sample compared with the population of the demographic surveillance area (DSA)

	Age (7 years)			Age (11 years)			Age (15 years)
	Full DSA	Present study	P value	Full DSA	Present study	P value	Full DSA	Present study	P value
Total (n)	1665	343*		1742	377‡		1864	357§
Electricity at home (%)	58·6	69·1	0·003†	57·5	60·5	0·414	59·0	63·6	0·200
Access to piped water (%)	56·2	60·1	0·31	55·5	57·8	0·524	56·4	63·3	0·06

*343 matched out of 514 = 66·7 %.

†Significant difference between DSA and present study.

‡377 matched out of 503 = 75·0 %.

§357 matched out of 502 = 71·1 %.