Table 4.

Do male adult-onset offenders, defined on the basis of first conviction, offend prior to adulthood? Unprosecuted antisocial behavior and police contact from childhood through late adolescence as a function of age-of-first-conviction group

	Age-of-first-conviction group			Test statistics
	Never Convicted1	Juvenile-onset2	Adult-onset3	Adult-onset vs Never convicted		Adult-onset vs Juvenile-onset
	Mean (SD)	Mean (SD)	Mean (SD)	t	p4	t	p4
Evidence of ASB during childhood
Parent and teacher reports of anti-social   behavior, age 5–11 years (z-score)5	−0.25 (.85)	.40 (1.15)	.21 (0.95)	3.91	<0.001	−1.16	0.124
	%	%	%	z	p4	z	p4
Evidence of ASB during adolescence
Conduct disorder diagnosis, age 11–18	14.1%	56.5%	33.8%	3.75	<0.001	−3.02	0.001
Any self-reported offending at age 13	29.5%	49.0%	46.5%	2.16	0.015	−0.27	0.392
Any self-reported offending at age 15	42.6%	56.0%	49.2%	0.93	0.180	−0.88	0.189
Any self-reported offending at age 18	46.7%	78.4%	74.2%	3.89	< 0.001	−0.64	0.260
Any self-reported offending, age 13–18	66.1%	88.4%	85.9%	3.12	<0.001	−0.50	0.310
Evidence of police contact up to age 18 years
Parent-reported police contact, age 13–15	3.4%	21.9%	16.7%	3.92	<0.001	−0.83	0.204
Police-recorded arrest before age 18	9.6%	38.4%	24.2%	3.23	<0.001	−2.00	0.023
Any adolescent ASB or police contact	65.4%	92.0%	84.9%	3.08	0.001	−1.58	0.057

Notes:

¹-No conviction by age 40 years, n=280.

²-First conviction age 14 to 19 years, n=138.

³-First conviction age 20 years and above, n=66.

⁴-p-values are one-tailed.

⁵-sex-standardized z-score.

Bold text indicates statistically significant difference; one-tailed p < .05.

ASB – antisocial behavior