Mothers and Children as Informants of Bullying
Victimization: Results from an Epidemiological Cohort
Sania Shakoor & Sara R. Jaffee & Penelope Andreou &
Lucy Bowes & Antony P. Ambler & Avshalom Caspi &
Terrie E. Moffitt & Louise Arseneault
Published online: 12 October 2010
# Springer Science+Business Media, LLC 2010
Abstract Stressful events early in life can affect children’s
mental health problems. Collecting valid and reliable
information about children’s bad experiences is important
for research and clinical purposes. This study aimed to (1)
investigate whether mothers and children provide valid
reports of bullying victimization, (2) examine the inter-rater
reliability between the two informants, (3) test the predic-
tive validity of their reports with children’s emotional and
behavioral problems and (4) compare the genetic and
environmental etiology of bullying victimization as
reported by mothers and children. We assessed bullying
victimization in the Environmental-Risk (E-Risk) Longitu-
dinal Twin Study, a nationally-representative sample of
1,116 families with twins. We collected reports from
mothers and children during private interviews, including
detailed narratives. Findings showed that we can rely on
mothers and children as informants of bullying victimiza-
tion: both informants provided information which adhered
to the definition of bullying as involving repeated hurtful
actions between peers in the presence of a power
imbalance. Although mothers and children modestly agreed
with each other about who was bullied during primary and
secondary school, reports of bullying victimization from
both informants were similarly associated with children’s
emotional and behavioral problems and provided similar
estimates of genetic and environmental influences. Findings
from this study suggest that collecting information from
multiple informants is ideal to capture all instances of
bullying victimization. However, in the absence of child
self-reports, mothers can be considered as a viable
alternative, and vice versa.
Keywords Informant.Bullying victimization.Agreement.
The selection of informants is pivotal in developmental
research to assess early-life stressors and their impact upon
children’s development. Low agreement between different
informants’ reports of emotional, behavioral and social prob-
on children’s experiences and behaviors (Achenbach et al.
1987; De Los and Kazdin 2005). Children provide self
perceptions and global views of their experiences across
various settings. However, relying on young children as
informants can be problematic. Some may be reluctant to
report stressful or embarrassing experiences such as bullying
victimization (Ladd and Kochenderfer-Ladd 2002; Olweus
2009). Furthermore, young children may not have yet
developed adequate cognitive abilities to comprehend the
concepts being assessed (Measelle et al. 1998), or recognize
their involvement in certain activities. The use of adults as
informants would counteract these limitations. However,
adults are largely dependent upon being informed about
children’s experiences as they often take place in their
absence. As both children’s and adults’ reports have some
drawbacks, it remains unclear who should be considered as an
S. Shakoor:S. R. Jaffee:P. Andreou:L. Bowes:A. P. Ambler:
A. Caspi:T. E. Moffitt:L. Arseneault (*)
MRC Social, Genetic and Developmental Psychiatry Centre,
Institute of Psychiatry, King’s College London,
Box Number p080, London SE5 8AF, UK
A. Caspi:T. E. Moffitt
Departments of Psychology and Neuroscience, Psychiatry and
Behavioral Sciences, and Institute for Genome Sciences and
Policy, Duke University,
Durham, NC, USA
J Abnorm Child Psychol (2011) 39:379–387
adequate informant of children’s stressful experiences such as
bullying. This study aims to test whether mothers and children
are valid and reliable informants for developmental and
Being bullied is a common stressful life experience
affecting on average 13% of children and adolescents
during a school year, worldwide (Craig et al. 2009).
Bullying behaviors are distinct from other forms of
aggressive behaviors. They are characterized by repeated
hurtful actions between peers where a power imbalance
exists. The repetition of these behaviors overtime results in
a pattern of interactions being established between victims
and bullies. These interactions are characterized by factors
which encompass a power imbalance (i.e. physical strength,
age or popularity), whereby it is difficult for the victim to
defend him or herself. These behaviors are manifested in
two ways (Olweus 1993, 1994); (1) direct, which includes
acts of aggression and assault that are conducted in a
relatively open manner, and (2) indirect, which includes
exclusion, social isolation and manipulation of friendship
groups. Researchers have observed gender differences
amongst these behaviors with direct bullying being more
frequent amongst boys, and indirect bullying more frequent
amongst girls (Card et al. 2008; Bjorkqvist et al. 1992;
Rivers and Smith 1994).
Being bullied can be a stable stressor in young children’s
lives (Barker et al. 2008a; Scholte et al. 2007) and
contributes towards their mental health problems. Victims
have reported elevated levels of emotional and behavioral
problems (Arseneault et al. 2006; Kim et al. 2005, 2006;
Nansel et al. 2004; Sourander et al. 2007; Wolke et al.
2000), self harm and suicidality (Barker et al. 2008a; Herba
et al. 2008; Klomek et al. 2009) and psychotic symptoms
(Arseneault et al. 2011; Schreier et al. 2009). These
associated adversities highlight bullying victimization as a
life stressor which requires attention. To fully capture the
impact of being bullied on children’s outcomes, we need to
ensure that research measures take into account the
specificity of bullying victimization by ascertaining that
reports adhere to its definition. We examined validity of
mothers’ and children’s reports of being bullied using
detailed narratives describing what happened.
Levels of agreement between informants who report on
children’s lives are generally low. Correlations ranging
between 0.25 and 0.40 have been reported between parents’
and children’s reports of emotional and behavioral prob-
lems (Achenbach et al. 1987; Rey et al. 1992; Sourander et
al. 1999) and 0.17 to 0.42 between parents and teachers
(Achenbach et al. 1987; Gross et al. 2004). However,
higher correlations have been found between mothers’ and
fathers’ reports of children’s behavior (r=0.60; Achenbach
et al. 1987). The modest correlations between children,
parents and teachers suggest that discrepancies in reports
from different informants do not alone reflect children’s
limited capacity to report accurately on their experiences.
Low agreement could be an indication that each informant
contributes unique and valuable information (Achenbach
2006). We investigated the agreement between mothers’
and children’s reports of being bullied during primary and
secondary school to establish inter-rater reliability.
Uncertainty regarding the validity of, and agreement
between, mothers’ and children’s reports of being bullied
raises questions about previously reported associations
between bullying victimization and children’s emotional
and behavioral problems. Studies have consistently shown
that victims of bullying have elevated levels of emotional
and behavioral problems in comparison to non-bullied
children (for a review see Arseneault et al. 2010). However,
these associations could be biased or spurious if they are
based on reports from informants who cannot provide valid
information about children’s bullying experiences. We
tested the predictive validity of mothers’ and children’s
reports of being bullied with emotional and behavioral
This uncertainty extends to etiological factors involved
in children’s predisposition to being bullied. Research
shows that being a victim of bullying is more than being
in the wrong place at the wrong time. A number of
individual, school and family risk factors contribute to
this risk (Arseneault et al. 2010). Studies have identified
exposure to domestic violence, child maltreatment (Bowes
et al. 2009), emotional and behavioral problems
(Arseneault et al. 2006; Barker et al. 2008b; Ladd and
Troop-Gordon 2003), low self worth and reduced asser-
tiveness (Egan and Perry 1998) to increase children’s risk
of being bullied. However, research investigating genetic
factors is limited. Based on information reported by
mothers, some evidence suggests that children have an
important genetic susceptibility to being bullied (Ball et al.
2008). In contrast, others using peer nominations, suggest
that being bullied is environmentally driven and unrelated
to a child’s genetic predisposition (Brendgen et al. 2008).
It remains unclear whether these findings are informant
specific. We compared genetic and environmental factors
involved in the etiology of mothers’ and children’s reports
of being bullied.
Trends in current research emphasize the importance
of reliably identifying bullying experiences early in life
as an important risk factor for children’s mental health
problems. There is growing evidence showing that
bullying victimization occurs not only amongst adoles-
cents but also amongst young children who have just
entered the schooling system (Barker et al. 2008b; Perren
and Alsaker 2006). As a consequence, bullying research
has witnessed a shift away from traditional school based
surveys of adolescents towards epidemiological cohorts of
380J Abnorm Child Psychol (2011) 39:379–387
young children. It is important to ensure that measures of
bullying victimization, are adapted to this change.
Using data collected from multiple informants in a
nationally-representative cohort of young twins, this study
aims to investigate whether mothers and children provide
valid and reliable reports of victimization.
Participants were members of the Environmental Risk (E-
Risk) Longitudinal Twin Study, which tracks the develop-
ment of a nationally-representative birth cohort of 2,232
British children. The sample was drawn from a larger birth
register of twins born in England and Wales in 1994–1995
(Trouton et al. 2002). Briefly, the E-Risk sample was
constructed in 1999–2000, when 1,116 families with same-
sex 5-year-old twins (93% of those eligible) participated in
home-visit assessments. Families were recruited to repre-
sent the UK population of families with newborns in the
1990’s, based on (a) residential location throughout
England and Wales and (b) mother’s age (i.e., older mothers
having twins via assisted reproduction were under-selected
and teen-aged mothers with twins were over-selected). We
used this sampling to (a) replace high-risk families who
were selectively lost to the register via non-response and (b)
ensure sufficient numbers of children growing up in high-
risk environments. Follow-ups were conducted when the
children were aged 7 years (98% participation, N=2,191),
10 years (96%, N=2,143) and, 12 years (96%, N=2,143).
Zygosity was determined using a standard zygosity ques-
tionnaire, which has been shown to have 95% accuracy (Price
et al. 2000). Ambiguous cases were zygosity-typed using
DNA. The sample includes 55% monozygotic (MZ) twins
and 45% dizygotic (DZ) twins. Sex is evenly distributed
within zygosity (49% male). Parents gave informed consent
and children gave assent. The Joint South London and
Maudsley and the Institute of Psychiatry Research Ethics
Committee approved each phase of the study.
We used mothers’ and children’s reports to assess bullying
victimization (hereafter referred to as “victimization”)
during primary and secondary school. We explained that
“someone is being bullied when another child (1) says
mean and hurtful things, makes fun or calls a person mean
and hurtful names; (2) completely ignores or excludes
someone from their group of friends or leaves them out of
things on purpose; (3) hits, kicks, or shoves a person, or
locks them in a room; (4) tells lies or spreads rumors about
them; and (5) other hurtful things like these. We call it
bullying when these things happen often, and it is difficult
for the person being bullied to stop it happening. We do not
call it bullying when it is done in a friendly or playful
way”. Mothers were interviewed when children were 7, 10
and 12 years, and were asked whether either twin had been
bullied by another child, responding “never”, “yes”, or
“frequent”. During interviews at age 7, mothers were asked
to report on their children’s experiences from school entry
at age 5. When victimization was reported, interviewers
followed by asking for details about what happened. For
example, a mother reported “at school, 2–3 boys in his
class, call him names, push and trip him up. This has been
happening every week”. We combined mothers’ reports at
age 7 and 10 to derive a measure of victimization during
primary school. Mothers’ reports at age 12 indexed
victimization during secondary school. The test–retest
reliability of reports of bullying was 0.87 using a sample
of 30 parents who were interviewed twice, 3 to 6 weeks
apart. When they were 12 years, children indicated during
private interviews whether they had been bullied by another
child and if this occurred in primary or secondary school.
We created a group of bullied children by combining
those who reported “yes” or “frequent” to being bullied.
The vast majority of bullying experiences occurred after
school entry, after the age of 5 years. A total of 43% of
children (N=956) were reported by their mother as having
been bullied during primary school and 36% (N=772)
during secondary school. Nearly 41% of children (N=871)
self-reported being bullied during primary school and 27%
(N=578) during secondary school. The present study
covers a period ranging from age 5 through to age 12
which is longer compared to other studies which have
reported lower prevalence rates (Craig et al. 2009).
Children’s Emotional and Behavioral Problems
We assessed emotional and behavioral problems when
children were 12 years using the Child Behavior Checklist
for mothers (Achenbach 1991a) and the Teacher’s Report
Form for teachers (Achenbach 1991b). Mothers were given
the instrument as a face-to-face interview and teachers
responded by mail. The reporting period was 6 months
before the interview. Informants were asked to rate each
item as being “not true” (0), “sometimes true” (1), or “very
true” (2). The emotional problems scale is the sum of 23
items from the CBCL and 27 items from the TRF on the
Withdrawn and Anxious/Depressed scales, including items
such as “cries a lot”, “withdrawn, doesn’t get involved with
others”, and “worries” (Somatic Complaints were not
included, as this scale was not assessed at age 12). Mothers’
scores ranged from 0 to 34 (M=6.45, SD=5.71) and
teachers’ scores ranged from 0 to 43 (M=4.51, SD=5.50).
J Abnorm Child Psychol (2011) 39:379–387 381
The internal consistency reliability score for mothers was
0.87 and 0.89 for teachers. The behavioral problems scale is
the sum of 35 items from the CBCL and 34 items from the
TRF in the Aggressive and Delinquent behaviors scales
including items such as “argues a lot”, and “is cruel or
nasty to other people”. Mothers’ scores ranged from 0 to 55
(M=10.14, SD=8.84), and teachers’ scores ranged from 0
to 56 (M=5.51, SD=9.50). The internal consistency
reliability score for mothers was 0.91 and 0.96 for teachers.
The mother and teacher reports were standardized and
summed to create composite measures of emotional and
behavioral problems at 12 years because mothers and
teachers provide unique information about children’s
behaviour and because simple combination riles work as
well, if not better than, more complicated ones (Bird et al.
1992; Piacentini et al. 1992).
Firstly, focusing on the bullied children only, we rated the
extent to which mothers’ and children’s reports of victim-
ization during secondary school showed evidence that
bullying was (1) perpetrated by peers, (2) repeated
instances over time and (3) occurred with a power
imbalance between the bully and the victim. These criteria
were coded as ‘1’ when there was evidence supporting the
criterion in the narratives and ‘0’ when there was not. When
no information was provided, narratives were coded as
missing. Using 96 mothers’ reports of victimization, we
found an inter-rater reliability kappa of 0.81 for the
behaviors being perpetrated by a peer, 0.92 for it being
experienced over time, and 0.82 for the presence of a power
imbalance. An overall inter-rater reliability kappa of 0.85
was observed between the raters across all 3 criteria.
The complete sample of children was used for the
remaining analyses. Secondly, we examined the agreement
between mothers’ and children’s reports of being bullied
during primary and secondary school by calculating the
percentage of cases where mothers and children agreed
with one another. We also calculated kappa coefficients.
Thirdly, we tested the associations between mothers’ and
children’s reports of victimization during primary and
secondary school with children’s emotional and behavioral
problems at 12 years with regression analyses controlling
for the effect of gender.
Fourthly, we compared etiological factors influencing
victimization from mothers’ and children’s reports using
tetrachoric correlations. Genetic and environmental influ-
ences on victimization were derived using Falconer’s
equation (Plomin et al. 2001). This equation stipulates that
the genetic contribution to victimization is estimated as
twice the difference between MZ and DZ correlations (A =
2(rmz– rdz)) where A is the genetic contribution, rmzis the
MZ twin correlation and rdzis the DZ twin correlation. The
contribution of the common environment (C) is the
difference between the MZ correlation and the genetic
estimate (C = rmz– A). The contribution of the unique
environment (E) is calculated by subtracting the MZ
correlation from 1 (E = 1 – rmz). We chose Falconer’s
equation in favor of structural equation modeling due to the
simplicity of the method and its ability to portray the
comparability in estimates using data from the two
We did not find significant gender effects across our four
analytical steps, thus all analyses were conducted collapsed
across gender. Each family contained data for two children,
which resulted in non independent observations. All
analyses adjusted for with tests based on the sandwich or
Huber/White variance estimator (Williams 2000). All
statistical analyses were conducted using Stata 9.0 (STATA
Construct Validity of Mothers’ and Children’s Reports
Mothers and children reported information which adhered
to the definition of victimization. When mothers reported
that their child had been bullied during secondary school,
96% recalled that bullying was perpetrated by peers, 75%
recounted it was repeated over time, and 84% reported
evidence of a power imbalance between the bully and the
victim. A total of 86% of mothers’ reports showed evidence
for at least 2 of the criteria for victimization. In comparison,
when children reported having been bullied during second-
ary school, 99% recounted the behaviors to have been
perpetrated by peers, 61% recalled bullying to have been
experienced repeatedly over time, and 81% reported
evidence of a power imbalance. A total of 85% of children
reported at least 2 of the criteria for victimization.
Inter-Rater Reliability Between Mothers’ and Children’s
Reports of Victimization
We found modest agreement between mothers’ and child-
ren’s reports of victimization experiences (Table 1).
Amongst 956 children identified by their mothers as being
bullied during primary school, 52% reported themselves
being bullied. Amongst 871 children who self-reported
being bullied, 56% were also identified by their mothers as
being bullied during primary school. Amongst 772 children
reported by their mothers to have been bullied during
secondary school, 45% agreed with these reports. In
contrast, amongst 578 children who reported being bullied
382J Abnorm Child Psychol (2011) 39:379–387
during secondary school, 60% were also identified by their
mothers as having been bullied. The kappa coefficient for
victimization was 0.20 during primary school and 0.29
during secondary school.
Predictive Validity of Mothers’ and Children’s Reports
of Victimization with Children’s Emotional and Behavioral
Victims of bullying, as identified by mothers and by
children, had significantly higher levels of emotional and
behavioral problems at age 12 when compared to non-
bullied children (Table 2). Mothers’ reports yielded slightly
larger effect sizes compared to those calculated using
children’s reports when victimization occurred during
primary school (0.39 vs. 0.17 for emotional problems;
0.27 vs. 0.15 for behavioral problems). When victimization
occurred during secondary school, effect sizes increased
for both informants and mothers’ reports still yielded
slightly larger effect sizes compared to those calculated
using children’s reports (0.57 vs. 0.42 for emotional
problems; 0.41 vs. 0.38 for behavioral problems).
Although overall effect sizes calculated using mothers’
reports were greater than those for children’s reports,
they were not significantly different as indicated by
overlapping confidence intervals.
Genetic and Environmental Influences on Mothers’
and Children’s Reports of Victimization
Estimates of genetic and environmental influences on
victimization were similar for both mothers’ and child-
ren’s reports (Table 3). At primary school, genetic
contribution to victimization was 0.54 using mothers’
reports and 0.32 using children’s reports while unique
environmental contribution was 0.31 according to moth-
ers and 0.43 for children. The contribution of common
environmental influences was 0.15 using mothers’ infor-
mation and 0.25 with details from children’s reports. For
both informants, genetic influences remained similar at
secondary school (0.47 for mothers vs. 0.40 for children).
Unique influences from the environment slightly de-
creased across time but remained similar across inform-
ants (0.21 for mothers vs. 0.34 for children). The estimate
for common environmental influences increased to 0.32
using mothers’ reports while the one using children’s
reports stayed close to the estimate in primary school
Table 1 Agreement between mothers’ and children’s reports of
Informant N (%)
Agreed by other
Table 2 Standardized scores of mothers’ and teachers’ combined rating of children’s emotional and behavioral problems at age 12 for bullied and
Bullied inInformant Non-bulliedBullied
Mean (SD)Mean (SD)
β (95%CI) Effect size (d)
Age 12 problems
0.39 (0.30, 0.48)
0.17 (0.08, 0.27)
0.23 (0.14, 0.33)
0.15 (0.05, 0.24)
Age 12 problems
0.57 (0.47, 0.68)
0.41 (0.30, 0.53)
0.39 (0.29, 0.50)
0.34 (0.22, 0.45)
All analyses were controlled for children’s gender
No interaction effect was observed between victimization and children’s gender
J Abnorm Child Psychol (2011) 39:379–387 383
Our study shows that mothers and children are valid and
reliable informants of victimization, a common early-life
stressor. Using data from a large representative cohort of
young children, findings indicated that mothers and
children report information which adheres to the definition
of victimization. Both informants reported information on
victimization that was similarly associated with children’s
emotional and behavioral problems. Estimates of genetic
and environmental influences on victimization were similar
for reports provided by mothers and children. Mothers and
children tended to agree with one another about who was
bullied in primary and secondary school, but they failed to
agree completely, therefore collecting data from multiple
informants is ideal to capture all instances of victimization.
However, in the absence of child self-reports, mothers can
be considered as a viable alternative, and vice versa.
Results indicated that both mothers and children report
information which matched the definition of victimization.
The lowest adherence to the definition and greatest discrep-
ancies between informants were observed for the ‘repeatedly
over time’ criterion. It is plausible that children, more so than
mothers, are mistaking single incidences of aggressive peer
behaviors (e.g. a playground fight) for bullying. Providing a
definition of bullying during the interview may help increase
accuracy and reduce confusion about the concept being
assessed.Collectinginformants’ narrativesmay alsobeuseful
for validating the data collected and cross-referencing the
information with the definition of bullying. Our research
protocol was not designed to gather narratives specifically in
relation to the 3 criteria for victimization. Future studies
should include probes targeting specific criteria to assess the
validity of bullying data.
In keeping with previous studies assessing informant
agreement of reports of emotional and behavioral problems
(Achenbach et al. 1987; Rey et al. 1992; Sourander et al.
1999), and victimization (Ladd and Kochenderfer-Ladd
2002; Ronning et al. 2009; Wienke Totura et al. 2009),
mothers’ and children’s reports of being bullied during
primary and secondary school overall yielded modest
agreement. Percentages of agreement calculated for our
study provided greater support of inter-rater reliability
compared to kappa coefficients. Taking into account that
kappa coefficients include the level of agreement between
those who are, and are not identified as being bullied, it is
plausible that mothers and children tend to disagree more so
about who is not being bullied rather than who is.
Kappa coefficients in the present study were higher than
those reported by other research assessing informants’
agreement on victimization (Ronning et al. 2009; Wienke
Totura et al. 2009). This may be attributable to the inclusion
of teachers as informants in other studies. When assessing
the agreement between children’s and teachers’ reports of
victimization, a kappa coefficient of 0.12 has been reported
(Wienke Totura et al. 2009). Similarly, kappa coefficients
ranging between 0.11 and 0.22 have been reported when
testing for the agreement between parents, teachers and
child informants. Based on these findings, it is possible that
when assessing bullying during childhood, mothers provide
more reliable information compared to teachers. This is
further supported by previous observations that children are
more likely to report bullying experiences to someone at
home than to their teachers (Whitney and Smith 1993).
However, as teachers’ reports of victimization were not
collected in this study, we could not verify this.
Although the agreement between mothers and children in
this study is low, they have both been shown to be valid;
therefore discrepancies between the informants are not likely
to be due to an error in the conceptualization of bullying
behaviors. Rather, it may reflect different information and
perspectives specific to each informant. For example, mothers
may be reporting more severe or apparent forms of victimi-
zation. Thus poor agreement is not necessarily a representa-
tion of poor reliability but could also indicate that each
informant contributes unique information (Achenbach 2006).
Discrepancies between mothers’ and children’s reports in
the current study were greatest for victimization during
Table 3 Genetic and environmental influences on bullying victimization according to mothers and children
Bullied in ZygosityEtiological influences
Correlation r (n pairs)
Correlation r (n pairs)
GeneticCommon environment Unique environment
Estimates for etiological influences were calculated using Falconer’s equation
384 J Abnorm Child Psychol (2011) 39:379–387
secondary school. This may indicate that children are
increasingly less likely to report bullying experiences to
adults as they get older. Parents may also be less aware of
what is happening in their child’s life as children become
more independent. Including children as informants when
they get older will be beneficial as the limitations
associated with mothers’ reports may become more
prominent when children enter adolescence. It is equally
important to include mothers as informants for young
children as the limitations associated with using young
children as informants may outweigh those of mothers.
Similar to previous studies, victims of bullying
showed elevated levels of emotional and behavioral
problems. Our study extends these findings by showing
the results are consistent whether victimization was
reported by mothers or children. The associations between
behavioral problems and victimization, as reported by both
mothers and children, did not significantly differ further
emphasizing the comparability between the two informants.
Discrepancies in effect sizes between mothers’ and children’s
reports of victimization, mostly in primary school, may be
explained by two factors. First, children’s reports collected at
age 12 may be biased by retrospective account of their
bullying experiences when they were in primary school.
Second, the slightly greater effect sizes observed when
mother reports of victimization were used may be due to
shared method variance, as mothers were informants of both
victimization and emotional and behavioral problems.
However, the associations using mothers’ reports are
unlikely to be spurious as significant associations were also
found when using children’s reports of victimization.
Furthermore, we observed slight increases in our effect sizes
when victimization was experienced during secondary
school. This may be explained by the shorter period of time
between the victimization experiences and emotional and
behavioral problems. Altogether, our findings indicate that
previous results of mental health outcomes of bullied
children are not likely to be informant specific and that
previous results which were based on the same informants to
report both victimization and the outcome could be slightly
We observed overall similar estimates of genetic and
environmental influences on victimization in primary and
secondary schools as reported by both mothers and
children. This finding supports previous reports indicating
substantial genetic influences on children’s risk of being
bullied (Ball et al. 2008) and further shows that this effect is
not dependent on the informant. These results demonstrate
that both informants’ reports tap into the same construct
and can therefore be considered as valid and reliable for
future research on the etiology of victimization. The slight
increase in common environmental influences for victimi-
zation during secondary school reported by mothers is
somewhat surprising given children’s growing indepen-
dence at the start of the adolescent years. It is possible that
twins are more likely to seek new environments with their
co-twin during this transitional period between primary to
secondary schools. Alternatively, it is possible that the fact
mothers reported on both twins’ experiences with victim-
ization resulted in inflated estimates of common environ-
Our study has a number of limitations which give rise to
further avenues of research. First, our investigation into the
validity and comparability of mothers and children as
informants was conducted on reports of only one type of
life stressor, bullying victimization. This raises the question
whether our findings can be generalized to other forms of
life stressors such as parental maltreatment or physical
abuse. Second, our study only investigated the agreement
between mothers and children. Further research is needed to
investigate the agreement between other informants, in-
cluding teachers and peers. In particular, as peers have often
been used to collect reports of bullying behaviors via peer
nomination methodology (Veenstra et al. 2007; Perren and
Alsaker 2006; Brendgen et al. 2008), bullying research
would benefit from validating peers as reliable informants.
Third, our sample included twins. We did not collect
information about twins’ experiences of victimization from
their co-twins. Our findings would have been strengthened
by including co-twins’ reports of bullying victimization.
Fourth, our measure of victimization during primary school
as reported by the child was retrospective. This may have
influenced our findings when comparing informants’
reports, as retrospective accounts may be biased by false
or distorted memories and by the current emotional state of
Whilst keeping these limitations in perspective, our find-
ings have research and clinical implications. Although our
findings support the comparability between mothers and
children as informants of victimization, the absence of
complete agreement between the two indicate that the use
of one informant would result in an incomplete account of
children’s lives. Our work emphasizes the need for multiple
informants for research and also in clinical settings.
Research would benefit from further enhancing methodo-
logical and statistical techniques used to incorporate and
optimize information from multiple informants. These
techniques include using mean scores, latent class factor
analyses, or an ‘either or’ approach. To further include
children’s perspective in research and clinical interviews,
J Abnorm Child Psychol (2011) 39:379–387385
developmentally appropriate measures that take into ac-
count limitations inherent to child self-reports are needed.
The use of games or puppets such as the Berkeley Puppet
Interview (BPI, Ablow et al. 1999) allows children to
express themselves and report on behaviors in a develop-
mentally sensitive manner. For mental health professionals
and researchers, although the reliance on one informant
alone does have limitations, our findings demonstrate that
in the absence of one informant the other can be considered
as a viable alternative. In situations where children are
unavailable or struggle to report on their experiences,
mothers can be considered as alternative sources of
information, and vice versa.
Research Council (MRC grant G9806489). Additional support was
provided by funds from the Johan Jacobs Foundation, the British
Academy, the Nuffield Foundation. Sania Shakoor is supported by the
Medical Research Council. Louise Arseneault is supported by a
Career Scientist Award from the Department of Health, UK. Lucy
Bowes is supported by the Economic and Social Research Council.
Avshalom Caspi is a Royal Society Wolfson Research Merit Award
holder. Terrie E. Moffitt and Avshalom Caspi are supported by the
Lady Davis Fellowship of the Hebrew University and The Caselberg
We are grateful to the study mothers and fathers, the twins, and the
twins’ teachers for their participation. Our thanks to Michael Rutter
and Robert Plomin, to Thomas Achenbach for kind permission to
adapt the Child Behavior Checklist, and to members of the E-Risk
team for their dedication, hard work, and insights.
The E-Risk Study is funded by the Medical
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