Table 1.

Characteristics of the study population by ethnicity

	Total population		Dutch		non-western immigrants
	N = 531		N = 258	48.6%	N = 273	51.4%
	mean		mean		mean	SD
age (years)	10.7	0.5	10.7	0.5	10.8	0.5
gender (# girls)	280	52.7%	133	51.6	144	54.8
Mother's educational level	N = 424	%	N = 232	%	N = 192
less than 7 years	52	12.3	5	2.2	47	24.5
7–9 years	45	10.6	14	6.0	31	16.1
10–12 years	98	23.1	64	27.6	34	17.7
more than 12 years	229	54.0	149	64.2	80	41.7