Table 1.

Participants

	Violent offender group	Control group
Nationalities	Dominican Republic, Iraq, Israel, 3 × Morocco, 3 × Netherlands Antilles, Pakistan, Republic of Cape Verde, 4 × Republic of Surinam, Serbia, 7 × The Netherlands, Trinidad and Tobago, 3 × Turkey, Yugoslavia	Armenia, Belgium, 2 × Canada, France, Germany, 4 × Indonesia, 2 × Iraq, Ireland, Nepal, Republic of Cape Verde, 2 × Republic of Surinam, Serbia, 9 × The Netherlands, 4 × Turkey
Education and work	3 only finished primary school	1 only finished primary school
	11 only finished high school	2 only finished high school
	11 finished MBO	10 finished MBO
	1 finished WO	8 finished HBO
	8 had to quit their study but might continue	2 finished WO
	6 were studying at MBO level in prison	4 studying at HBO/WO level
	26 worked in prison	5 unemployed
Mean age	31.65 years, range 19–61 years old	32.31 years, range 18–62 years old

In the Netherlands, the highest finished education of the male population was at the time of testing about 10 % primary school, 50 % high school, 20 % bachelor degree, 15 % master degree. Of those, 4 % was unemployed

WO = Masters’ degree at science university. Can only be entered after 6 years of highest level high school

HBO = Bachelors’ degree at non-science university. Can be entered after 5 years of medium level high school

MBO = 2–3 year practical school which starts after 4 years of lowest level high school