Experimental Design
We recruited participants and their parents from the two cities Cologne and Bonn in Germany. In 2011, we invited all families living in those cities with children born between September 2003 and August 2004 to participate in a mentoring program, as well as one third of families with children born between September 2002 and August 2003 (N=14,451). We truthfully informed parents that, due to capacity constraints, participation in the program was not guaranteed. 1626 families indicated a willingness to participate and answered a short questionnaire including questions on income, education and whether both parents lived in the same household. We focus on those children whose parents met at least one of the following three criteria: (i) Equivalence income of the household is lower than 1065 Euro, corresponding to the 30th percentile of the German income distribution. (ii) Neither parent has a school-leaving degree qualifying for university studies. (iii) Parents do not live in the same household. We invited these children (N=700) and their parents for a baseline interview conducted in September to October 2011. 590 children and their parents participated in the baseline interview and gave their written consent to allow the transmission of their address to the organization running the mentoring program. This is our main sample. Out of this sample, 212 families were randomly selected to be treated (“treatment group”), the remaining 378 families form the control group.
We also recruited a high socio-economic status (SES) comparison group from the children whose parents did not meet either of the three criteria listed above (N=150 invited, N=122 participated in the baseline interview and gave written consent).