Workshop in Biostatistics

Medical School Office Building (MSOB)
Rm x303

DATE: September 28, 2017
TIME: 1:30 - 2:50 pm
TITLE: A Behavior-Based Intervention that Prevents Sexual Assault: The Results of a Matched-Pairs, Cluster-Randomized Study in Nairobi, Kenya
Mike Baiocchi
Assistant Professor
Stanford Prevention Research Center (Primary) and,
by courtesy, Depts of Statistics and Health Research & Policy, Epidemiology, Stanford



We can prevent gender-based violence. An interdisciplinary team here at Stanford is developing rigorous, empirical evidence to inform the development of these prevention programs. In this talk we discuss the results of a cluster-randomized, matched-pairs, parallel trial of a behavior-based sexual assault prevention intervention in the slums of Nairobi, Kenya. The participants were primary school girls aged 10-16. Classroom-based interventions for girls and boys were delivered by instructors from the same settlements, at the same time, over six 2-hour sessions. The girls’ program had components of empowerment, gender relations, and self-defense. The boys’ program promotes healthy gender norms. The control arm of the study received a health and hygiene curriculum. The primary outcome was the rate of sexual assault in the prior 12 months at the cluster level (school level). Secondary outcomes included the generalized self-efficacy scale, the distribution of number of times victims were sexually assaulted in the prior period, skills used, disclosure rates, and distribution of perpetrators. Difference-in-differences estimates are reported with bootstrapped confidence intervals.

Fourteen schools with 3147 girls from the intervention group and 14 schools with 2539 girls from the control group were included in the analysis. We estimate a 3.7 % decrease, p = 0.03 and 95 % CI = (0.4, 8.0), in risk of sexual assault due to the intervention (initially 7.3 % at baseline). We estimate an increase in mean generalized self-efficacy score of 0.19 (baseline average 3.1, on a 1–4 scale), p = 0.0004 and 95 % CI = (0.08, 0.39).

We will discuss several methodological innovations that have been developed during this study. We will also point to several other outstanding methodological questions our team is working on.

Suggested reading:

Michael Baiocchi, Benjamin Omondi, Nickson Langat, et al.  A Behavior-Based Intervention that Prevents Sexual Assault: the Results of a Matched-Pairs, Cluster-Randomized Study in Nairobi, Kenya.  Prevention Science, pp 1-10.  First online: 25 August 2016.