To examine the intensity of CSA psychological effects or correlates, we first
meta-analyzed the sample-level effect sizes from the 54 samples for which these could be
computed (sample-level effect sizes are listed in the Appendix ).
[*3]
[*3] Appendixes containing other effect sizes for other analyses in the Results
section (i.e., symptom-level, moderator analyses, male-female differences, family
environment-CSA relations, and family environment-symptom relations) can be obtained by
writing to Bruce Rind.
The resulting
unbiased effect size estimate, based on 15,912 participants, was r u=
.09, with a 95% confidence interval from .08 to .11. Because this interval did not include
zero, the obtained result was statistically significant (i.e., SA students were less well
adjusted than controls). This difference in adjustment between SA and control students was
small, however, according to Cohen's (1988) guidelines; in terms
of variance accounted for, CSA accounted for less than 1% of the adjustment variance.
A chi-square test of the homogeneity of the sample-level effect sizes revealed
that they were not homogeneous, chi 2 (53) = 78, p < .01.
In an
attempt to achieve homogeneity, we examined the distribution of sample-level effect sizes
to determine whether outliers existed. We defined outliers to be effect sizes that were at
least 1.96 standard deviations away from the unweighted mean effect size (i.e., falling in
the extreme 5% of the distribution).
Three outliers were found ( r = .36 in Jackson
et al., 1990 ; r = .40 in Roland et al., 1989 ; r = -.25 in
Silliman, 1993 )
with z scores of 2.71, 3.16, and -3.60, respectively.
The Jackson et al. study
included only incest cases in the CSA group, and the Roland et al. study included a large
proportion of incest cases. Moreover, Neumann et al. (1996) also found the Roland et al.
result to be an outlier.
Measures used in these studies from which effect sizes were
computed included:
the SAS, BDI, RSE, and DSFI ( Jackson et al., 1990 );
the MMPI form R (
Roland et al., 1989 ); and
the LOC and TSCS ( Silliman, 1993 ).
These measures were all
used in other studies whose effect sizes were not outliers, implying that the outlying
results were not a function of these measures. Removing these outliers resulted in
homogeneity, chi 2 (50) = 49.19, p > .50, based on k = 51
samples, with N = 15,635 subjects.
The recalculated unbiased effect size estimate (r
u= .09) and the 95% confidence interval (.08 to .11) were unchanged after
rounding. The obtained small unbiased effect size estimate implies that, in the college
population, the magnitude of the relationship between CSA and adjustment is small, which
contradicts the assumption that CSA is associated with intense harm in the typical case.
Next we examined the magnitude of the relationship between CSA and adjustment at
the symptom level.
Table 3 presents the
results of the 18 symptom-level meta-analyses. The table shows for each meta-analysis the
number of independent samples ( k ), the total number of participants in these
samples ( N ), the unbiased effect size estimate (r u), the 95%
confidence interval of r u, and the homogeneity statistic ( H )
based on the chi-square test.
Initial meta-analyses yielded 8 homogeneous and 10 heterogeneous results. In an
attempt to achieve homogeneity with heterogeneous sets, we examined the distribution of
effect sizes within each of these sets to detect outliers, as defined previously. We
removed all such deviant effect sizes and then recomputed the meta-analyses. If
homogeneity was achieved in a particular set, then the search for outliers stopped for
that set. Otherwise, the
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reduced set of effect sizes was examined for new outliers, and, if found, the
outliers were removed and the meta-analysis was performed again.
If the set of effect
sizes was still heterogeneous and no additional outliers were found, the set was
considered to be heterogeneous. This procedure resulted in achieving homogeneity in 7 of
the 10 initially heterogeneous sets, yielding 15 out of 18 homogeneous sets.
Effect sizes
remained heterogeneous only for hostility, self-esteem, and sexual adjustment.
Of the 9
effect sizes removed in the 7 sets that became homogeneous, the majority came from two of
the studies that contributed to the heterogeneity of effect sizes in the sample-level
meta-analysis-5 from Roland et al. (1989) and 1 from Jackson et al. (1990) . These six
effect sizes and one additional effect size from Bendixen et al.'s (1994) female sample
were removed from the upper end of their distributions. Two effect sizes were removed from
the lower end of their distribution ( Fishman, 1991 ; Fromuth & Burkhart, 1989 ,
Southwest sample).
Measures on which removed effect sizes were based in Jackson et al.'s
and Roland et al.'s studies were listed previously in the sample-level meta-analysis
section; Bendixen et al. and Fishman used investigator-authored items, whereas Fromuth and
Burkhart used the SCL-90-R. Many studies with nonoutlying effect sizes used
investigator-authored items and the SCL-90-R, implying that the outlying results were not
a function of the measures used.
In Table 3 , the original
numbers (i.e., number of samples, number of participants in these samples, unbiased effect
size estimate, and homogeneity statistic) associated with the heterogeneous results for
the seven sets that became homogeneous are shown in parentheses, whereas the numbers
associated with the reduced homogeneous sets appear directly under the column headings.
Removing outliers showed itself to be productive in achieving homogeneity; further, this
procedure had little effect on effect size estimates, indicating that the large majority
of effect size estimates can be considered to be reliable estimates of true effect sizes
in the college population.
The unbiased effect size estimates for all 18 symptoms were
small according to Cohen's (1988) guidelines. The
effect size estimates ranged from r u= .04 to .13. Despite these
small values, all effect size estimates, except for one (locus of control), were
statistically significantly greater than zero, as is indicated by their 95% confidence
intervals.
These findings indicate that, for all symptoms but one, CSA participants as a
group were slightly less well adjusted than control participants. The small magnitude of
all effect size estimates implies that CSA effects or correlates in the college population
are not intense for any of the 18 meta-analyzed symptoms.
Table 3
Meta-Analysis of 18 Symptoms Associated With Child Sexual Abuse From College
Samples
