Table 2.

Bivariate analyses comparing grade average in the last trimester for boys only

Variable	Grades 13 and above (above average grades) n = 377 % (n) or mean (SD)	Grades 12 and below (average and below average grades) n = 587 % (n) or mean (SD)	Statistic	P value
Age	17.2 (1.6)	18.0 (1.6)	t949 = -7.74	0.0005
	n = 371	n = 580
Days absent in the last 30 d
Not absent	56.1% (211)	39.4% (230)
1 d	13.8% (52)	17.6% (103)
2 d	12.5% (47)	12.7% (74)	χ52 = 31.15	0.0005
3-4 d	7.4% (28)	11.3% (66)
5-6 d	2.9% (11)	5.7% (33)
7 or more days	7.2% (27)	13.4% (78)
	n = 376	n = 584
Father’s education level
Not educated	19.5% (66)	27.5% (142)
Elementary school	16.3% (55)	18.2% (94)
Middle school	6.2% (21)	11.8% (61)	χ42 = 28.09	0.0005
High school	21.6% (73)	20.7% (107)
College and beyond	36.4% (123)	21.9% (113)
	n = 338	n = 517
Mother’s education level
Not educated	36.3% (127)	46.0% (251)
Elementary school	14.3% (50)	15.0% (82)
Middle school	7.7% (27)	9.0% (49)	χ42 = 22.22	0.0005
High school	16.9% (59)	17.0% (93)
College and beyond	24.9% (87)	13.0% (71)
	n = 350	n = 546
Socioeconomic status compared with other families in country
Above other families	26.1% (98)	17.2% (101)
Same as other families	68.5% (257)	74.8% (439)	χ22 = 12.40	0.002
Below other families	5.3% (20)	8.0% (47)
	n = 375
Ever used alcohol, hashish, psychotropic, or other drugs	33.7 (127)	44.8 (263)	χ2 = 11.78	0.001
Age first used alcohol, hashish, or psychotropic drugs	15.0 (2.4)	16.0 (2.0)	t310 = -3.66	0.0005
	n = 98	n = 214
Used alcohol, hashish, or psychotropic drugs in the last 12 mo	17.0 (64)	23.3 (137)	χ2 = 5.63	0.018
Used alcohol, hashish, or psychotropic drugs in the past 30 d	10.9 (41)	17.0 (100)	χ2 = 6.98	0.008