Relationships and Health 425relationships seems to be mutual (Prospero &
Kim, 2009). A study that examined physical
assault among students from 31 colleges that
spanned 16 countries showed that the me-
dian (50th percentile) percentage of physical
assaults among dating couples over the last
year was 29%, ranging from a low of 17% to a
high of 45%, which was detected in a univer-
sity in the United States (Straus, 2004). The
incidence of physical assault in some of the
countries is shown in Figure 11.11. Female
perpetration rates were higher than male
perpetration rates in 21 of the 31 universities.
A meta-analytic review of sex differences in
physical aggression in heterosexual romantic
relationships showed a small effect in the di-
rection of females being more aggressive than
males (d 52 .05; Archer, 2000). However,
the age of the sample was an important mod-
erator, such that females perpetrated more
aggression than males in younger samples
(age 22 and younger,d 52 .12), and males
perpetrated more aggression than females in
older samples (age over 22,d 51 .12).
Findings are similar among high
school students and middle school stu-
dents. In a study of a racially diverse group
of high school students, women and men
were equally likely to report being victims of
violence (about 30%), and women reported
that they perpetrated violence more than
men (40% vs. 24%; O’Leary et al., 2008).
However, two-thirds of the violence was
mutual. Unilateral violence was more likely
to occur in the instance of female than male
perpetrators (27% vs. 5%), as reported by
both females and males. The rate of injury
was the same for women and men. The least
physical aggression occurred among Asians
compared to Whites, Hispanics, and African
Americans. A study of sixth graders showed
that females were more likely than males
to initiate violence in relationships withWomen initiate as much as or more IPV
compared to men. A nationally representa-
tive survey showed that women reported re-
ceiving and perpetrating more violence than
men, but the violence was mutual in half
the relationships (Williams & Frieze, 2005).
In the past, when similar rates of IPV were
found between females and males, research-
ers suggested that female IPV was more likely
to be characterized as self-defense than male
IPV. However, this is not true (Carney et al.,
2007; Dutton, 2007). There is no evidence
that female perpetration of violence is more
likely to be characterized by self-defense, and
females are just as likely as males if not more
likely to strike first (Felson & Cares, 2005).
A meta-analysis of physical aggression
in heterosexual couples showed that females
were more likely to throw, slap, kick/bite/
punch, and hit their partners with an object
compared to males—as reported by both
females and males (Archer, 2002). Males
were more likely to beat up and choke or
strangle their partners. The overall sex dif-
ference in rates of perpetration, favoring fe-
males, was even stronger in younger samples,
in particular high school and college groups.
IPV among dating couples appears to
be similar to research on adult married and
cohabiting couples. A five-year longitudinal
study of over 2,000 college students in the
United States showed that 26% of college
students experienced physical IPV in their
freshman year (Nabors & Jasinski, 2009).
Again, females reported that they perpe-
trated more violence than males (30% vs.
18%). Over the course of the study, women
were 2.5 times more likely than men to say
they engaged in IPV. In two smaller stud-
ies of college students, there was no sex
difference in perpetration of IPV (Gratz
et al., 2009; Katz, Kuffel, & Coblentz, 2002).
Again, the majority of IPV in college studentM11_HELG0185_04_SE_C11.indd 425 6/21/11 12:43 PM