Table 1. General characteristics of students in the three schools.

Characteristics	School A (n) n = 808	School B (n) n = 44	School C (n) n = 381	Total (n) n = 1,233
Educational stage (n)
Kindergarten	121	2	-	123
Primary school	448	42	-	490
Secondary school	239	-	381	620
Sex (n)
Male	370	18	137	525
Female	438	26	244	708
Age (years)a
Range	4 to 19	4 to 12	11 to 24	4 to 24
Average	10.9	9.8	15.4	12.2

^aA few Hill-tribe students started school significantly later than other Thai children.