Table 1.

Demographic and family-related characteristics (in % of total) of the study population (6- to 17-year-old Clalit Health Service members) in 2011, according to relative age in class

	Children’s relative age in class
	Oldest third N = 251 093	Middle third N = 245 710	Youngest third N = 270 974
Overall (%)	32.7	32.0	35.3
Sex (%)
Boy	16.6	16.4	18.1
Girl	16.1	15.6	17.2
Age, years (%)
6 to 8	9.0	8.9	9.5
9 to 11	8.5	8.3	9.1
12 to 14	8.0	7.9	8.5
15 to 17	7.2	7.0	8.1
Ethnic sector (%)
General Jewish	18.4	17.8	19.8
Arab	12.5	12.6	13.6
Ultra-Orthodox Jewish	1.7	1.6	1.9
Birth order among siblings (%)
First	9.3	10.5	10.8
Second to third	18.4	17.2	19.4
Fourth or subsequent	5.0	4.3	5.0
Number of children in family (%)
1 to 2	5.7	5.7	6.4
3 to 5	19.6	19.6	21.4
6 or more	7.5	6.7	7.5
SES (%)
Low	17.5	17.0	18.9
Mid	10.4	10.2	11.2
High	4.4	4.4	4.8

SES, socioeconomic status at the health clinic level.