Groups (school)

Frequency

Age (years)

Class (frequency/%)

Age p-value

(n)%

mean ± S.E.M

First

Second

Third

Missed

Academic

945 (79.6)

16.1 ± 0.1

269 (28.5)

317 (33.5)

357 (37.8)

2 (0.2)

control

Co-academic

123 (10.4)

18.4 ± 1.2

1 (0.8)

16 (13)

106 (86.2)

-

<0.0001

Commercial

62 (5.2)

16.5 ± 0.2

25 (40.3)

20 (32.3)

17 (27.4)

-

0.1

Technical

57 (4.8)

16.6 ± 0.2

31 (54.4)

23 (40.4)

3 (5.3)

-

0.07