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A summary of the evidence supporting Empowerment Self-Defense as violence prevention on college campuses (and one study about bystander intervention)

10.05.16 by Amy Jones

Empowerment self-defense is the umbrella term for the approach to self-defense that we teach at Thousand Waves. Other “empowerment self-defense” (or ESD) programs include IMPACT Chicago (and other IMPACT chapters), the programs that the Center for Anti-Violence Education runs in Brooklyn, the programs run by sister school Sun Dragon Martial Arts & Self-Defense in Austin, Texas, Hand to Hand Kajukenbo Self-Defense in Oakland, and many others across the country. Basically, it’s the idea that self-defense should help participants live with more confidence and less fear by helping them identify and strengthen their self-defense skills, giving them accurate information about violence, and supporting them in making choices that make sense for their life.

We teachers of ESD have felt strongly for years that it’s a great way to empower our participants to reduce violence in their own lives and communities. While there have been articles on the efficacy of self-defense generally in the academic literature for quite a while, it has only been in the past few years that we’ve started to see academic studies that look carefully at empowerment self-defense courses specifically.

There have been four studies published in the last 3 years that I’m going to summarize below, and I’ll follow each with a short commentary. But first, some context for those of you who don’t swim in social science research waters all the time: things to look for in any good social science study is sample size, the presence of a control group and randomization. A sample size is the number of participants who experienced the intervention (self-defense training or bystander intervention training, in our case). A control (or comparison) group is a comparable group of people who don’t receive the intervention, and it’s important because it controls for outside factors. For example, if over the period you’re studying, a war starts — or more happily, a war ends — that will certainly create changes that have nothing to do with what you’re trying to measure. Those changes should show up in both your sample and your control/comparison group.

Random assignment into control group vs. sample group — or more broadly, into participation vs. non-participation — helps you know that your participants represent the larger population, because everyone in the larger population has an equal chance of experiencing the intervention – so any special characteristic (like elevated fear, for example) is just as likely to be in the sample AND the control/comparison. This can be especially tricky with something like self-defense training, because most people who take a self-defense class choose to do so – which makes them ‘the type of person who takes a self-defense class,’ and it’s reasonable to think that the type of person who takes a self-defense class might do other things that make it less likely that they’ll be the victims of assault.
Below is a summary of studies that have looked at ESD programs in structured and repeatable ways.

Study: Efficacy of a Sexual Assault Resistance Program for University Women
Author: Senn, et al.
Published in: The New England Journal of Medicine, June 11, 2015
Sample: 430 first-year women from 3 Canadian universities
Control Group: 420 first year women from the same 3 universities who received brochures on sexual assault
Randomization: Random assignment was used; sample and control were recruited from the pool of research participants (approximately 70% of students on campus) as well as posters, emails from professors, and class presentations.
The ESD Training: Four 3-hour trainings delivered either over a single weekend (6 hours/day), or 4 weeks
Results: At 1-year follow-up, risk of completed rape was reduced by 46.3% (5.2%  vs. 9.8% control)
Commentary: The presence of a sizeable sample, control group, and randomization makes this a very strong study. One rarely sees effect sizes this large for any intervention. This study only came out last year, but I hope to see researchers replicating this approach, because it shows ESD to be extremely effective.

Study: A Self-Defense Program Reduces the Incidence of Sexual Assault in Kenyan Adolescent Girls
Author(s): Sinclair, et al.
Published In: Journal of Adolescent Health (2013)
Participants: 381 high school girls in the Korogocho district of Nairobi, Kenya
Control Group: 108 High school girls in the Kariobangi North district of Nairobi, Kenya, which has similar population demographics to Korogocho.
Randomization: This was a non-randomized study. Instead, it was census-based, which means that all female students in the districts were invited to participate.
The ESD Training: 6-week, 12-hour training, followed by 2-hour refresher courses at 3, 6, 9, and 10 months.
Results: At 10-month follow-up, rape among those who received the ESD training decreased from 24.6% to 9.2%. This represents a 62.6% decrease in rape. For the control group, the incidence of rape remained unchanged.
Commentary: This is another strong study, despite its lack of randomization, because the deciding factor was not the students’ own self-selection, but their geographic location (and the study authors made sure to select two regions that had similar demographic characteristics, as well as rates of victimization before the training) – and within the location, all students were invited to participate, so the sample size and population size was in this case the same. Another (heartbreaking) aspect that makes this a strong study is the incredibly high incidence of rapes amongst these girls.

Study: Does Self-Defense Training Prevent Sexual Violence Against Women?
Author: Jocelyn Hollander
Published in: Violence Against Women, 2014, Vol. 20 (3) 252-269
Sample: 117 students recruited from a self-defense class offered at a state university in the Pacific Northwest
Control Group: 169 students in unrelated classes (such as English, Dance, Biology, and Geography)
Randomization: no randomization, students self-selected to take the self-defense class
The ESD Training: 3 hrs/week for 10 weeks, plus 1.5 hours of discussion/week (45 hours total)
Results: At 1-year follow-up, sexual victimization of any kind — defined as unwanted sexual contact, sexual coercion, attempted rape, or rape —  among those who received the ESD training was 12%, compared to 30.6% of the control group. This represents over a 50% difference between the two groups. Additionally, no women who received ESD training reported completed rape, compared to 2.8% of the control group.
Commentary: This study isn’t as rigorous as the first two, since students self-selected into self-defense training. Still, the fact that the results are not that different from the Senn study or the Sinclair study implies that the self-selection bias may not have had a significant effect on the results.

Study: Evaluation of the Green Dot Bystander Intervention to Reduce Interpersonal Violence Among College Students Across Three Campuses
Author(s): Coker, et al
Published In: Violence Against Women (2014)
Participants: 2,018 college students on a campus who received some form of Green Dot Bystander Intervention
Control Group: 4,258 college students on a campus without Green Dot
Randomization: “stratified random sampling,” which means random sampling, but based on year in school (25% first-year students, 25% second-year, etc)
The ESD Bystander Intervention Training: The training included two components: 1,122 sampled students heard VIP staff give a 50-minute motivational speech in an introductory-level course. 2) 448 students sample received intensive training (training length was 4-6 hours)
Results: This study was looking at two things: both whether incidence of violence was lower at the intervention campus overall, and whether victimization or perpetration of violence was less amongst those who had received the training.

At 9-month follow-up, students at the Green Dot campus overall were victimized 9% less often than students at the comparison campus, and perpetration was significantly lower among males on the Green Dot campus.

No significant differences were observed in violence perpetration rates among those Green Dot trained and those who received no training. Women who received intensive training had a 13% lower victimization rate compared to those who received no training.
Commentary: This study isn’t looking at ESD training, instead it looks at a popular bystander intervention training. It’s rigorous in that it uses random sampling, and it has a large sample size. The effect of the training was positive, if not as large as the ESD studies. Of course, one thing that the Green Dot study does measure is a diffusion effect  — incidence of violence is lower overall on the campus that received the intervention.  Studies looking at ESD training haven’t measured that.  If I were making decisions based on the academic literature, I would certainly consider investing in Green Dot – but I would prioritize ESD. Even better would be to look at the two interventions used together.

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