Sustained effects of incredible years as a preventive intervention in preschool children with conduct problems.

Abstract

The present study evaluated preventive effects of the Incredible Years program for parents of preschool children who were at risk for a chronic pattern of conduct problems, in the Netherlands. In a matched control design, 72 parents of children with conduct problems received the Incredible Years program. These families (intervention group) were compared with 72 families who received care as usual (control group). Two years after termination of the intervention, it appeared that observed and selfrated parenting skills were significantly improved in the intervention group. Likewise, in this group, observed child conduct problems showed sustained intervention effects. The decrease in observed critical parenting mediated the decrease in observed child conduct problems over time. In addition, it appeared that parental influence increased over time.

Full text

Page 1

Sustained Effects of Incredible Years as a Preventive
Intervention in Preschool Children with Conduct Problems
Jocelyne A. Posthumus & Maartje A. J. Raaijmakers &
Gerard H. Maassen & Herman van Engeland &
Walter Matthys
Published online: 18 October 2011
# The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract The present study evaluated preventive effects of
the Incredible Years program for parents of preschool
children who were at risk for a chronic pattern of conduct
problems, in the Netherlands. In a matched control design,
72 parents of children with conduct problems received the
Incredible Years program. These families (intervention
group) were compared with 72 families who received care
as usual (control group). Two years after termination of the
intervention, it appeared that observed and selfrated parenting
skills were significantly improved in the intervention group.
Likewise, in this group, observed child conduct problems
showed sustained intervention effects. The decrease in
observed critical parenting mediated the decrease in observed
childconduct problems overtime. Inaddition, itappearedthat
parental influence increased over time.
Keywords Prevention.Conduct problems.Aggressive
behavior.Parent management training.Preschoolers
Introduction
Conduct problems are very common in early childhood.
However, a high level of conduct problems in young
children has been found to be relatively stable over time,
and can be seen as a risk factor for the development of
conduct disorders (e.g., Coté et al. 2006; Tremblay et al.
2004; Shaw et al. 2005). In addition to the negative
developmental consequences of conduct disorders for the
individual, such as poor school, interpersonal, and occupa-
tional adjustment, substance abuse, delinquency and other
psychiatric disorders (Kim-Cohen et al. 2003; Maughan and
Rutter 2001), conduct disorders also incur high costs to
society (Raaijmakers et al. 2011; Scott et al. 2001a).
Moreover, the majority of children and adolescents in mental
health services are referred because of severe conduct
problems (Kazdin and Weisz 2003).
Early prevention of conduct disorders has become an
important goal for authorities in child development and
those who provide community mental health services.
Hence, intervention programs targeting preschool children
with a high level of conduct problems have been devel-
oped. Addressing parenting practices is considered a
valuable starting point for prevention, since ineffective
parenting, consisting of physical punishment, inconsistent
discipline and poor responsiveness to the child (Farrington
2005; Webster-Stratton and Taylor 2001), is associated with
Jocelyne A. Posthumus and Maartje A. J. Raaijmakers equally
contributed to the study and they therefore share first authorship.
J. A. Posthumus:M. A. J. Raaijmakers:H. van Engeland:
W. Matthys
Department of Child- and Adolescent Psychiatry, Rudolf Magnus
Institute of Neuroscience, University Medical Centre Utrecht,
Utrecht, The Netherlands
M. A. J. Raaijmakers
Department of Developmental Psychology, University of Utrecht,
Utrecht, The Netherlands
G. H. Maassen
Department of Methodology and Statistics, University of Utrecht,
Utrecht, The Netherlands
J. A. Posthumus
De Waag, Center for Forensic Psychiatry,
Utrecht, the Netherlands
J. A. Posthumus (*)
Department of Child and Adolescent Psychiatry,
University Medical Centre Utrecht,
Kruisweg 16 bis,
3513 CT, Utrecht, The Netherlands
e-mail: jocelyneposthumus@hotmail.com
J Abnorm Child Psychol (2012) 40:487–500
DOI 10.1007/s10802-011-9580-9

Page 2

the development and persistence of conduct problems
(Patterson 1982; Patterson et al. 2002), whereas effective
parenting, consisting of praise and the use of appropriate
discipline techniques such as time out (Gardner et al. 2006;
Webster-Stratton and Taylor 2001) serves as a protective
factor (Tremblay et al. 2004).
Behavioral Parent Training (BPT), which positions the
parent as the primary agent for change, is proven to be the
most effective method in reducing conduct problems,
particularly in young children (McCart et al. 2006). One
of these BPT’s is the Incredible Years Videotape Modeling
Program (IY; Webster-Stratton 2001a, b; Webster-Stratton
and Hancock 1998) aimed at improving parenting skills in
order to reduce children’s problem behavior. This program
consists of two components; the BASIC component
addresses play, praise and rewards, limit setting and handling
misbehavior. Parents are taught to use child directed play
skills, to use less critical statements and harsh discipline, and
to increase the use of positive and consistent strategies. The
ADVANCE component (Webster-Stratton 2002) elaborates
on the BASIC program and covers topics such as how to
cope with upsetting thoughts and depression, communication
skills and solving problems with adults and children.
ADVANCE has shown to corroborate the effects of the
BASIC program (Webster-Stratton 1994).
Originally, the IYprogram was designed for the treatment
of conduct disorders in young children, and it has proven
effectiveinreducingsevereproblembehavior(e.g.,Scottetal.
2001b; Taylor et al. 1998; Webster-Stratton and Hammond
1997; Webster-Stratton et al. 2004). However, whether the
IY program is also effective as a preventive intervention is
less clear.
Indeed, studies into the effectiveness of the IY parent
program as a preventive intervention yield various results,
especially with respect to changes in child behavior. On the
one hand, there are studies that reported decreases in child
problem behavior; some studies reported positive effects
either on parent or on teacher rated measures (Hutchings et
al. 2007; Patterson et al. 2002), some only on observed
child behavior (Brotman et al. 2008, 2009; Webster-Stratton
1998), and some on both measures (Barrera et al. 2002;
Webster-Stratton et al. 2001). On the other hand, in several
studies the preventive effectiveness of the IY program on
child behavior was not demonstrated (Kratochwill et al.
2003; Reid et al. 2007; Scott et al. 2010); no differences
between the intervention and control groups on (observed
or parent reported) child behavior were found in these
studies. Furthermore, most of these studies into the
preventive effect of IY have only investigated the effec-
tiveness of the BASIC program, often in samples with
relatively low socioeconomic status, conducted follow up
for a relatively short period of time, and showed a low
attendance rate (e.g., Reid et al. 2007; Scott et al. 2010).
The present study aimed to evaluate the effectiveness of
the IY parent program as an intervention to prevent a
chronic pattern of conduct problems in preschool children.
Our study is novel and contributes to the current literature
regarding the preventive effectiveness of the IY parent
program in several ways. First, to establish solid preventive
effects it is necessary to conduct long term follow-up
assessments. Therefore, relatively long follow-up assess-
ments, up to 2 years after termination of the intervention,
were conducted to evaluate the preventive effects of the IY
program in the current study.
Second, this study evaluates both the BASIC and AD-
VANCE component of the IY program. Most evaluations of
theIYparentprogramhaveonlyinvestigatedtheeffectiveness
of the BASIC program. Furthermore, since we limited the
intervention in this study to the program for parents, results
found can be attributed only to the IY parent program, in
contrast to studies in which additional programs were used.
Third, in addition to parent-rated measures, an observa-
tion of parent–child interaction was conducted as a more
objective measure of child behavior. Parent-ratings of child
behavior are often susceptible to biases, such as parents’
mood or expectations of the intervention (Eddy et al. 1998)
and observations have been found to be sensitive to change
in parent and child behavior as a result of an intervention
(Aspland and Gardner 2003; Frick and Loney 2000).
Finally, the present study adds to the existing knowledge
by examining mediation mechanisms. Mediation was
examined to investigate whether improvements in parenting
skills preceded the changes in child behavior, as suggested
by Kazdin and Nock (2003). Additionally, bidirectional
influences of parenting skills and child behavior over time
were studied.
Method
Design
A case control design, in which participants were selected
to be in either the intervention group (IG) or control group
(CG) based on their place of residence, was used in this
study. Randomization was not feasible because of geo-
graphical reasons. According to the Standards of Evidence
given by the Society for Prevention Research (2005), use of
a case control design is permitted “as long as assignment
was not by self-selection, but instead by some other factor
(for instance geography)”. The families to be recruited lived
in several different towns and cities in the province of
Utrecht, The Netherlands. As motivation to participate is a
recurrent problem in intervention studies, especially when
families of children with conduct problems are involved
(Luk et al. 2001), every effort was made to encourage
488J Abnorm Child Psychol (2012) 40:487–500

Page 3

families to participate. To avoid low attendance rates due to
the location of the training, the IYprogram was delivered at
four different sites which were within 15 km distance from
the consenting families’ homes and which are also easily
accessible, such as community centers. Moreover, the IY
program requires at least 6 parents to participate in a parent
group to optimize discussion and to foster a sense of support
(Webster-Stratton 2001a, b). Consequently, sufficient parents
had to live in the same area to form a group. In addition,
parents in the control group were blind to their condition,
i.e., they were not informed on the fact that the other group
received a parent program. The control group instead was
told that the study aimed to investigate the development of
aggressive behavior in young children and that they would
be informed on the study design after completion of the
study. CG parents were allowed to use regular services for
their child’s behavior, i.e., care-as-usual, and were informed
about the design of the study retrospectively. Families of the
two conditions were matched on the child’s gender, level of
aggression, IQ, the parents’ educational level, stress level,
and address density of the place of residence of the family. In
a separate study, the performance of a case control design
was compared to a randomized study design by simulating
hypothetical intervention and control groups in a mathemat-
ical software program based on the data in the present study.
The Mahalanobis metric was used to assess the distance
between families in the IG and CG and pairwise matching
was performed. The equivalence of the predefined interven-
tion and control group was compared to the equivalence of
the randomized groups, resulting in a more equally balanced
distribution of the six key characteristics in our matched
predefined groups than in randomization in more than half of
the simulated trials, indicating that matching in a case control
design was a viable alternative for this study (Raaijmakers et
al. 2008). Therefore, in the present study, the same matching
procedure was executed. In this study, families were assessed
at pre-intervention (PRE), directly after termination of the
intervention (POST), one year after termination of the
intervention (FU1) and two years after termination of the
intervention (FU2).
Participants
Addresses of families were acquired by the Office for
Screening and Vaccination in the province of Utrecht, The
Netherlands. Parents of 16002 4-year-old children born
either in 2000 or 2001 received a Child Behavior Checklist
1½–5 (CBCL; Achenbach and Rescorla 2000; Dutch
version by Verhulst & Van der Ende) by mail. More than
half of the parents filled out and returned this questionnaire
(see Fig. 1). Children were selected to participate if they
scored at or above the 80th percentile of the Aggressive
Behavior scale of the CBCL. In total, 503 children scored at
or above the 80th percentile and were considered to show
conduct problems. Based on their place of residence, 277
families were selected for the IG and 226 families for the
CG. First, rural and urban areas were identified, based on
address density data, resulting in eight urban and eight rural
areas. Then, those areas were divided between the
intervention and control group. The intervention groups
were recruited from four urban and four rural areas, and the
control group families were recruited from four other urban
and four rural areas. Parents were invited to participate by
letter and were called maximally 2 weeks later to ask for
their response. If parents were interested in participation,
two research team members visited the family to explain
the procedure of this research project. During this home
visit, families who were invited to participate in the
intervention received additional information on the IY
parent program. Children with an estimated full scale IQ
below 80 were excluded from the study. This resulted in 72
families (26% of the selected families) in the IG and 110
families (47% of the selected families) in the CG.
Reasons for non-participation were: 1) experiencing
stressors (IG: 10%, CG: 18%, e.g. chronic illness of a family
member, pressure of a partner to decline), 2) parents found
treatment/the study not relevant (IG: 39%, CG: 42%, e.g.
parents indicated they were capable of handling their child’s
aggressive behavior, lackofparentalrecognition ofthe child’s
aggressive behavior), 3) parents found treatment/the study too
demanding (IG: 23%, CG: 9%, e.g. parents did not want to
commit themselves to a 3-year study), 4) practical reasons
(IG: 23%, CG: 24%, e.g. involvement in other interventions,
child diagnosed with another disorder, i.e., 4 autism spectrum
disorders, 1 Prader Willi) and 5) parents indicated no reason
(IG:5%,CG:7%).TheAggressiveBehaviorscoreofchildren
whose parents agreed or refused to participate in this study
was not significantly different, neither in IG, nor in CG.
Mahalanobis person to person matching was performed
after PRE on 72 IG families and 72 CG families. An
independent administrator who was not involved in this study
carried out the matching procedure. Families lost between
POST to FU2 (3 CG and 2 IG) did not differ in their initial
level of aggression from those retained. Attrition of these
families was due to personal circumstances such as medical
conditions of the child or parent, or participation was a too
heavy burden for the family.
Characteristics of the IG and CG are presented in Table 1.
At selection, the mean percentile of the CBCL aggressive
behavior score was the 93rd percentile. Groups did not
significantly differ on any of these descriptive characteristics,
except for age of the child, t (71)=2.41, p=0.018; CG
children were 2 months older than IG children. All primary
caregivers were biological parents, except for one mother in
the IG, who was an adoptive parent. Almost all children
were Caucasian except for three IG children (one from South
J Abnorm Child Psychol (2012) 40:487–500489

Page 4

America, two from Asia) and one CG child (from South
America). At PRE, all children were medication naïve. All
families were allowed to use care as usual. Twelve families
in IG (17.9%) and 11 CG families (15.7%) received other
professional help during the intervention phase. The families
received mental health care (7 IG children, 5 CG children),
youth care (2 IG children, 5 CG children), educational
support (4 IG children, 7 CG children), and community care
(3 IG parents, 5 CG parents). In addition, the researchers
offered their help in finding adequate mental health services
when needed. Questionnaires and home observations were
conducted with the primary caregiver of the child. In the IG,
18% of the primary caregivers were fathers and in the CG,
10% of the primary caregivers were fathers.
Procedure
Prior to PRE, written informed consent was obtained from
the participating families. Every assessment consisted of a
set of questionnaires, which was mailed to the parents, and
N = 503
Aggression > 80th %tile
N = 277
Invited for intervention
72 IG
Pre assessment
N = 226
Invited for Control Group
110 CG
Pre assessment
N = 8632 (41%)
Returned CBCL 1½ - 5
N =16002
Received CBCL 1½ - 5
8129
Aggression < 80th %tile
INTERVENTIONCARE AS USUAL
MATCHING
PROCEDURE
72 CG
Post assessment
72 IG
Post assessment
71 IG
1- year- follow up
70 CG
1- year- follow up
70 IG
2- year- follow up
69 CG
2- year- follow up
Fig. 1 Flow chart of selection
and assessments
490J Abnorm Child Psychol (2012) 40:487–500

Page 5

a home visit. Home visits consisted of an observation of the
primary caregiver and the child playing together. Parents
received a monetary reward (€ 25,-) for each assessment.
The study was approved by the Medical Ethical Review
Committee of the Utrecht University Medical Center.
The Incredible Years Parent Program: BASIC
and ADVANCE
In this study, the BASIC and ADVANCE curriculum were
delivered in 18 2-hour sessions (11 BASIC and 7
ADVANCE). Eight groups of parents received the inter-
vention in community centers in different towns and cities
spread over the province of Utrecht. The parent groups
were led by two certified group leaders with parents of 6 to
11 children per group. Parents were encouraged to attend
the group together. If parents missed a session, group
leaders called them, sent them home assignments, and
encouraged parents to come to the next session half an hour
earlier in order to discuss the content of the missed session.
After termination of the IY program, two booster sessions
were offered 3 months and 6 months after termination of
the intervention. In the weekly sessions, parents watched
approximately 225 brief vignettes of parents and children
interacting. After each vignette, the group leader asked
questions to stimulate discussion about what parents found
particularly (in)effective and to practice alternative responses.
Dutch subtitles were used in the video-vignettes. Parents were
encouraged to role-play new skills and to practice these skills
at home in order to establish new habits. Before each session,
parents read a chapter on the topic of that particular session in
the book belonging to the program.
Teaching methods wereusedwithina collaborative setting,
in which group leaders established themselves as part of the
group, rather than as experts. Parents were empowered due to
the group process and the collaborative attitude of the
therapist.Groupleadersencouragedparentstosolveproblems
in order to ensure that the progress made during the
intervention was maintained after program completion.
Treatment Fidelity and Integrity
Treatment fidelity has been demonstrated to be a predictor
of positive change (Bellg et al. 2004). Therefore, it is
crucial to ensure the intervention program is delivered as
originally intended. Six members of the team, with a
background in clinical child psychology or child psychiatry,
were trained by the program developer during a 3-day
workshop. The members of the research team ran two pilot
groups at child psychiatry settings to become familiar with
the materials and specific techniques, and they received
supervision from accredited IY trainers to become certified.
Intervention sessions were videotaped and reviewed during
weekly meetings of group leaders to ensure that the
program was delivered with fidelity. In addition, a quarter
of the video taped sessions was peer-reviewed. Finally, the
manual of the IY program was used and both parental
evaluations as well as checklists for group leaders were
filled out after every session.
Measures
Child Behavior Checklist (CBCL 1½–5)
The CBCL 1½–5 (Achenbach and Rescorla 2000) is a
parent-rated questionnaire, consisting of 99 items, on which
the child is rated on various behavioral and emotional
problems. The CBCL 1½–5 consists of 7 subscales in
which the items can be clustered, i.e., Emotionally
Reactive, Anxious/Depressed, Somatic Complaints, With-
drawn, Sleep Problems, Attention Problems and Aggressive
Behavior. By summing all the item scores, a Total Problems
score is computed. Parents circle the answer that fits the
behavior of their child; “never”, “sometimes” or “always”.
The CBCL is widely used in clinical and research settings
because of its demonstrated reliability and validity, ease of
administration and applicability to clinical and nonclinical
groups (Dutra et al. 2004). To recruit the children, the level
of conduct problems was assessed using the Child Behavior
Checklist 1½–5 Aggressive Behavior scale (Achenbach and
Rescorla 2000). This scale contains 19 items like “hits
Table 1 Sample characteristics by group
MeasureIG
(n=72)
M (SD)
CG
(n=72)
M (SD)
Child
Gender (% boys)
Age (months)
IQ
CBCL 1½–5
(raw scores at selection)
Aggressive Behavior
Parent
Age (years)
Primary caregiver
Secondary caregiver
Education (%)
Primary
Secondary
Intermediate vocational
Higher vocational
University
70.8
50.3 (3.11)
107.3 (9.87)
70.8
51.3 (2.53)
107.5 (11.57)
21.99 (4.37)22.49 (4.69)
35.5 (4.84)
37.9 (5.12)
34.1 (5.49)
36.8 (4.83)
–
4.2
29.2
38.9
27.8
2.8
5.6
31.0
31.0
29.6
Education denotes the highest educational level of both parents.
J Abnorm Child Psychol (2012) 40:487–500491

Page 6

others”, “does not feel guilty” and “often has temper
tantrums”.
Eyberg Child Behavior Inventory (ECBI)
The ECBI (Eyberg and Pincus 1999) is a parent-rated
questionnaire used to assess the occurrence of conduct
problems in children aged 2 to 16 years. Several studies
have demonstrated acceptable reliability and validity of the
two scales (e.g., Boggs et al. 1990; Eyberg and Pincus
1999; Rich and Eyberg 2001). The ECBI consists of 36
behavioral items which are rated on two scales; an Intensity
Scale, which measures the frequency of the problem
behavior on a 7-point scale (ranging from ‘never’ to
‘always’; in the present study, α=0.91) and a Problem
Scale, which asks parents to report whether the behavior is
perceived to be a problem (yes or no; α=0.88).
Dyadic Parent–child Interaction Coding System - Revised
(DPICS-R)
The DPICS-R (Eyberg and Robinson 1981; revised 2000)
is an observational measure used to assess the quality of
parent–child interactions at home, with adequate psycho-
metric properties (Robinson and Eyberg 1981). Parent and
child were observed for 20 min while playing with a fixed
set of toys at PRE, POST and FU assessments. The
observation was videotaped and coded later on. The
observation consisted of four five-minute periods; in the
first period parent and child played like they would usually
do to get used to being videotaped, in the second period the
child picked a toy and directed the play session (child
directed play, CDI), in the third period the parent picked a
toy and directed the play session (parent directed play,
PDI), and in the final period the parent had to make the
child clean up (clean up, CU). For each period, parenting
skills and child behavior were coded separately into 47
categories; 24 for parent behavior (e.g., statements, positive
affect) and 23 for child behavior (e.g., physical warmth,
smart talk). In this study, parental behavior categories
Critical Statements and Labeled Praise were used. With
respect to child behavior, a composite score of the
categories Smart Talk, Cry/Whine/Yell, and Physical
Negative was used. This composite score was labeled
Conduct Problems (α=0.51). In addition, the category
Comply was used as a measure of child behavior. A
proportional compliance-score was constructed; the number
of the child’s comply-scores was divided by the number of
parental commands. Trained master-students and trained
project staff had to achieve an interrater-reliability of 70%
before coding parent and child behaviors into these
categories. Coders were blind to condition. The quality of
scoring was monitored continuously by having 20% of the
observations checked by a second rater. Double checking
the observations revealed a mean interrater-reliability of
80% (SD=5.20, range: 70–96%).
Parent Practices Interview (PPI)
This parent-rated questionnaire (Webster-Stratton 2001)
was designed to measure parenting skills or discipline
styles of parents of young children. The PPI consists of 15
questions, each with several aspects, asking for a response
of the parent to misbehavior, appropriate behavior and
several statements. Parents could answer to these questions
and respond to the statements on a seven-point Likert-scale,
ranging from ‘not (likely) at all’ to ‘always/very likely’.
Seven summary scales are extracted from this question-
naire; Appropriate Discipline (e.g., actually disciplining the
child when it misbehaves, 12 items, α=0.74), Harsh and
Inconsistent Discipline (e.g., threatening, but not punishing,
15 items, α=0.81), Positive Verbal Discipline (e.g., discus-
sing the problem with the child, 9 items, α=0.67),
Monitoring (e.g., supervision of child activities, 5 items,
α=0.35), Physical Punishment (e.g., slapping or hitting
when misbehavior occurs, 6 items, α=0.87), Praise and
Incentives (e.g., giving a hug or compliment, 11 items, α=
0.73), and Clear Expectations (e.g., clear rules about going
to bed, 6 items, α=0.65). All scales demonstrated accept-
able reliability, except for Monitoring. Therefore, this scale
was excluded from the analyses.
Data Analysis
Since there was a low level of attrition, missing data were
not imputed. If a scale score was missing for a family, that
scale score of the matched family was removed from the
analyses as well. Scale scores were excluded from the
analyses if more than 25% of the items of a scale of a
measure were missing. Four PPI’s were missing because of
that reason; two IG and two CG mothers did not fully fill
out that questionnaire. Overall intervention effects were
evaluated by means of a repeated measures ANOVA using
Helmert contrasts of the time x group interaction (which is
tantamount of Helmert contrasts of the IG-CG difference
scores across time levels). This contrast compares the mean
of the dependent variable at each level of the independent
variable (i.e., assessment) with the overall mean of the
dependent variable at the subsequent levels of the indepen-
dent variable. If the intervention effect is present and
sustained, this will show in the following way in the
Helmert contrasts: PRE versus all later assessments will
significantly differ; POST versus all later assessments, as
well as FU1 versus FU2, will not significantly differ. Time
was entered as a within subject factor and because of
matching, group was entered as a within subject factor as
492 J Abnorm Child Psychol (2012) 40:487–500

Page 7

well. A criterion of p<0.05 was used in the analyses.
Analyses were performed with SPSS 15.0. Due to technical
problems in the video registration of the observations of
parent–child interactions, less DPICS data were gathered at
PRE than at POST, FU1 and FU2. Moreover, five families
were lost from POST to FU2 (3 CG and 2 IG children). As
a consequence, 56 pairs of children in the PRE to FU2
DPICS comparisons were analyzed. Mediation is demon-
strated by means of structural equation modeling (SEM).
Results
Comparisons at PRE
ANOVA’s revealed no significant differences between IG
and CG on the parent rated measures at PRE. However, on
observed behavior of parents and children several signifi-
cant differences between IG and CG were found. Parents
differed on Critical Statements, with IG parents being more
critical than CG parents, F=3.99, df=1, p=0.050. Children
differed significantly on Conduct Problems, F=8.68, df=1,
p=0.004. IG children showed more conduct problems than
CG children at PRE.
Attendance
Attendance rate was 78%; an average of 14 sessions (out
of 18) was attended by at least one of the parents.
Groups were attended by couples (43%), single mums
(14%), parents who alternated (12%), fathers (6%; while
mother stayed at home) and mothers (25%; while father
stayed at home). None of the families dropped out of the
intervention.
PRE to FU2 Comparisons
Sample sizes, means and standard deviations for IG and CG
are presented in Table 2. Results of the repeated measures
ANOVA are presented in Table 3.
DPICS: Observed Parenting
The development in Critical Statements revealed a pattern
that is indicative of a sustained intervention effect. The
decrease in Critical Statements was significantly larger in
the IG than in the CG between PRE and all other moments
of assessment, while no significant difference between
POST and later moments were ascertained. This means that
the effect on Critical Statements occurred between PRE and
POST. The IG showed a significantly larger increase of
Labeled Praise at POST, but this effect disappeared
between POST and FU1.
DPICS: Observed Child Behavior
Repeated measures ANOVA’s revealed that there were no
differences between IG and CG on Comply between PRE
versus later moments of assessment, between POST versus
all later moments of assessment and between FU1 and FU2.
Thus, no sustained effects on Comply was found. A
difference emerged between FU1 and FU2 in favor of the
CG; the CG showed a larger increase on Comply than the
IG. Further, the IG showed a larger decrease on Conduct
Problems between PRE and all later assessments than the
CG, while the differences between POST and all later
moments of assessment and between FU1 and FU2 did not
significantly differ, which is indicative of sustained inter-
vention effects. This means that the effect on Conduct
Problems occurred between PRE and POST.
PPI: Parent-rated Parenting
Repeated measures ANOVA’s revealed several significant
differences indicative of sustained effects in parenting skills
between the IG and CG. Sustained intervention effects on
Appropriate Discipline, Harsh and Inconsistent Discipline
and Praise and Incentives were found. All effects pointed
in the expected direction, with the IG showing larger
improvements in these skills than the CG between PRE and
all later moments of assessment.
ECBI: Parent-rated child Behavior
No significant differences between IG and CG were found
over time.
Mediation
As a consequence of the results described earlier, the
question of whether improvement of parental skills medi-
ated the improvement of child conduct has been constricted
to the question of whether the decrease in Critical State-
ments led to a decrease in Conduct Problems. More
specifically, the question to be answered is whether the
improvement in Critical Statements (i.e., the change from
PRE to POST) would indeed precede the improvement in
Conduct Problems (i.e., the change from PRE to FU2).
Because of the matching of IG with CG, it was not possible
to conduct traditional mediation analyses according to
guidelines of Baron and Kenny (1986), as is customary in
mediation analyses. We also tested a path model, but we
were forced to design a model that is based on the use of
difference scores, analogous to the earlier reported repeated
measures ANOVAs.
With regard to the dependent variable (improvement of
Child Conduct), difference scores were computed be-
J Abnorm Child Psychol (2012) 40:487–500 493

Page 8

Table 2 Mean scores of outcome measures in IG and CG from PRE to FU2
N
PRE
POST
FU 1
FU2
IG
CG
IG
CG
IG
CG
IG
CG
M (SD)
M (SD)
M (SD)
M (SD)
M (SD)
M (SD)
M (SD)
M SD)
Observed
Parenting: DPICS
Critical statements
56
8.64 (8.05)
6.07 (4.74)
4.70 (5.03)
5.29 (4.61)
3.21 (3.27)
4.41 (4.57)
3.00 (3.56)
3.50 (4.02)
Labeled praise
56
0.52 (0.85)
0.45 (0.78)
1.86 (2.95)
0.46 (0.71)
1.07 (1.72)
0.55 (1.35)
0.50 (0.92)
0.43 (0.74)
Child Behavior: DPICS
Comply
56
40.80 (15.75)
45.07 (13.90)
36.46 (15.70)
39.25 (17.13)
53.47 (14.71)
46.31 (11.28)
48.63 (14.22)
49.18 (15.21)
Conduct problems
56
9.11 (13.62)
3.88 (5.62)
3.93 (6.65)
2.86 (5.04)
1.91 (4.68)
0.98 (2.02)
1.29 (2.19)
0.80 (1.62)
Parent-rated
Parenting: PPI
Appropriate discipline
66
49.36 (10.36)
49.86 (8.87)
54.00 (9.47)
48.83 (9.21)
53.06 (7.79)
49.50 (8.67)
53.39 (9.26)
48.55 (7.96)
Harsh and incons.discipline
66
45.93 (9.60)
44.53 (10.04)
39.28 (7.41)
43.07 (9.53)
40.95 (9.73)
42.67 (10.41)
39.65 (9.17)
42.33 (9.84)
Positive verbal discipline
66
49.95 (6.21)
48.62 (5.91)
51.26 (5.14)
48.85 (5.91)
50.73 (6.34)
48.47 (6.99)
50.33 (5.31)
49.07 (6.19)
Physical punishment
66
9.57 (4.46)
10.48 (4.63)
7.93 (3.93)
9.90 (4.50)
7.77 (2.15)
8.74 (3.59)
7.43 (1.71)
8.40 (2.86)
Praise and incentives
66
46.65 (7.74)
45.21 (7.04)
52.78 (6.74)
44.14 (6.81)
50.52 (5.76)
42.91 (6.96)
50.85 (6.05)
43.54 (7.56)
Clear expectations
66
21.87 (3.79)
21.47 (3.79)
22.20 (3.91)
21.27 (2.66)
23.410 (3.85)
22.19 (4.71)
24.39 (4.77)
22.83 (4.23)
Child behavior: ECBI
Intensity
53
126.70 (25.15)
128.06 (28.04)
117.96 (26.92)
122.60 (29.28)
120.55 (25.67)
122.62 (25.34)
118.34 (24.46)
118.53 (25.23)
Problem
43
12.30 (6.96)
11.72 (7.96)
9.93 (6.83)
10.91 (8.91)
11.74 (8.17)
10.70 (7.71)
10.58 (7.38)
10.16 (7.76)
494J Abnorm Child Psychol (2012) 40:487–500

Page 9

tween PRE and FU2 (PRE was subtracted from FU2) for IG
and CG; then, the scores of the CG were subtracted from the
scores of the IG for each matched pair. With regard to the
independent variable (improvement of Critical Statements),
Glasnapp (1984) was followed, who advocates inclusion of
both components of the change score as separate predictors
in a regression analysis. The most important reason is that a
straight change score (i.e., equal weights with opposite sign)
is less than an optimum predictor. The model used to
investigate mediational mechanisms is presented in Fig. 2.
The coefficient from Critical Statements at PRE to the
difference from PRE to FU2 on Conduct Problems was
negative, B=−0.60, p<0.001, while the coefficient from
Critical Statements at POST to the difference from PRE to
FU2 on Conduct Problems was positive, B=0.38, p<0.001.
These results can be expressed in the following formula:
CP FU2 ? PRE
verbally, improvement of child conduct shown at FU2,
which is expressed as a negative CP(FU2-PRE) score, is
positively related to gain of parental skills achieved between
PRE and POST, also resulting in a negative value of a
weighted difference between the amounts of critical state-
ments uttered at the two moments. These results indicate that
decrease in Critical Statements due to the IYparent program
during the intervention (PRE to POST) led to a decrease in
Conduct Problems 2 years after termination of the interven-
tion. It appeared that the decrease in Critical Statements
mediated the decrease in Conduct Problems.
ðÞ ¼ 0:38»CS POST
ð Þ ? 0:60»CS PRE
ðÞ. Put
Table 3 Interaction effects of the repeated measures ANOVA with Helmert contrasts
PRE versus all later assessmentsPOST versus all later assessments FU 1 versus FU2
FpFpFp
Observed
Parenting: DPICS
Critical statements
Labeled praise
Child Behavior: DPICS
Comply
Conduct problems
Parent-rated
Parenting: PPI
Appropriate discipline
Harsh and inconsistent discipline
Positive verbal discipline
Physical punishment
Praise and incentives
Clear expectations
Child behavior: ECBI
Intensity
Problem
6.67
8.19
0.012
0.006
0.13
10.86
0.716
0.002
0.60
2.02
0.442
0.161
3.26
4.65
0.076
0.035
2.63
0.11
0.111
0.746
5.78
0.54
0.020
0.466
12.21
13.63
0.49
0.40
29.02
1.99
0.001
0.000
0.484
0.530
0.000
0.163
0.63
1.39
0.58
2.77
1.29
0.39
0.429
0.244
0.451
0.101
0.262
0.531
1.58
1.05
1.49
0.00
0.09
0.23
0.214
0.310
0.230
1.00
0.772
0.635
0.10
0.12
0.756
0.732
0.99
1.57
0.324
0.217
0.28
0.23
0.598
0.631
Critical Parenting
POST
Conduct Problems
PRE to FU2
Critical Parenting
PRE
- .60 **
.38 **
.29 *
* p < .05
** p < .001
Fig. 2 Mediation of critical
parenting on child conduct
problems
J Abnorm Child Psychol (2012) 40:487–500495

Page 10

In addition, we conducted longitudinal analyses in order to
test the bidirectional influences of parenting skills and child
behavior over time. Therefore, a cross-lagged panel model
with parenting skills and child behavior measured at four
distinct moments in time was designed. In this model,
difference scores between the IG and CG were used. Since
observed Conduct Problems was the only child behavior
outcome that improved at FU2 and Critical Statements was
the only observed parenting skill that improved at FU2, a
model with observed Critical Statements and Conduct
Problems from PRE to FU2 was constructed. Note that,
when compared with the CG, the IG showed a signifi-
cantly larger decrease on both Conduct Problems and
Critical Statements. In the initial model, we included
stability coefficients of Critical Statements and Conduct
Problems. Further, it was predicted that both parents and
children would influence each others behavior, both cross-
sectionally and longitudinally. The bidirectional influences
could not be assessed cross-sectionally because such a
model did not result in a convergent solution. Since it was
expected that parental influence on child behavior would
be larger than influence of child behavior on parenting
skills, in the final model only cross-sectional influences of
parenting skills on child behavior were hypothesized. As a
result of the IY parent program, we predicted the child’s
influence to decrease and the parent’s influence to increase
over time. In order to make the model fit (after
considering the modification indices), relations were
added. (CFI=0.958; RMSEA=0.057; Chi²=14.66; df=10;
see Fig. 3).
In this model, the added relations, relative to the hypothe-
sized relations, are represented as dotted lines (Standardized
Direct, Indirect and Total Effects are presented in Table 4).
Against expectations, the ANOVA’s revealed that the IG and
CG significantly differed on Critical Statements and Conduct
Problems at PRE. Therefore, the influences of PRE on
assessments at subsequent moments are indeed not hypoth-
esized, but added and presented as dotted lines. The
difference between IG and CG on Critical Statements was
relatively stable over time (from POST to FU2), and the
difference between IG and CG on Conduct Problems
appeared to be stable between FU1 and FU2. The cross-
sectional influence of the difference between IG and CG on
Critical Statements on the difference between IG and CG on
Conduct Problems was moderate at POST, and very weak at
FU1 and FU2. The influence of the difference between IG
and CG on Critical Statements at POST on the difference
between IG and CG on Conduct Problems at FU1 was weak,
while the influence of the difference between IG and CG on
Critical Statements at FU1 on the difference between IG and
CG on Conduct Problems at FU2 was moderate. This model
indicates that the influence of critical parenting on negative
child behavior increased over time, while the influence of the
child’s conduct problems on critical parenting remained
relatively small.
Discussion
In the present study, the 2 year follow up effects of the
Incredible Years program for parents of 4-year old children
who were at risk for the development of a chronic pattern of
conduct problems was evaluated. As expected, the results
showed significant improvements in both observed and
parent-rated parenting skills in the IG when compared to
the CG, and these improvements were maintained over
time. The observation of parenting behavior revealed a
sustained decrease in the use of critical statements 2 years
after termination of the intervention. The increased use of
labeled praise after the intervention, however, disappeared
over time. Parents themselves reported sustained increases
in appropriate discipline and praise, whereas they reported
sustained decreases in their use of harsh and inconsistent
discipline. In addition, observed child behavior showed
sustained positive intervention effects; children showed less
conduct problems 2 years after the intervention. In contrast,
parents did not report improvements in child behavior. It
should be noted that IG children had significantly higher
conduct problem scores at PRE than CG children, and IG
parents scored significantly higher on the use of critical
statements than CG parents. Thus, there was a greater
chance of regression to the mean in the IG. This difference
was corrected for by using repeated measures ANOVA’s
with time x group interaction. However, there still might
have been a larger possibility of improvement in the IG. In
addition, although the number of drop outs during the
intervention phase was zero, the number of cases in some
measures at later assessments was relatively low. Therefore,
these findings must be interpreted with caution. Further,
evidence for parenting practices mediating changes in child’s
conduct problems was demonstrated; i.e., the decrease in
critical parenting during the intervention due to the IYparent
program led to a decrease in the child’s conduct problems
2 years after termination of the intervention. Additional
analyses in which the bidirectional influences of parenting
skills and child behavior were investigated revealed that the
influence of parenting skills on child behavior increased over
time, while the influence of the child’s behavior on parenting
skills remained weak over time.
Although parents continued to use less criticism towards
their children 2 years after termination of the intervention,
they did not praise their children as much as they did directly
after termination of the intervention. One might speculate that
parents did takethe child’s complianceforgranted and did not
feel urged to go on praising such behavior. By contrast,
persistent use of less criticism might be easier for parents,
496 J Abnorm Child Psychol (2012) 40:487–500

Page 11

maybe because they immediately observe the negative effect
of criticism on their child’s emotions.
No differences between IG and CG children on parent
reported conduct problems were obtained. The discrepancy
between parent reported and observed changes in child
behavior was reported in earlier studies (Brotman et al.
2008; Gardner et al. 2006). The lack of a parent reported
decrease of the child’s conduct problems might be due to a
difference between the two groups in motivation to report
these problems. Compared with parents who did not
participate in the intervention, parents in the IY parent
program learn to observe their child’s behavior and to
identify their child’s problems as goals in the IY parent
program (Webster-Stratton 1998). One might speculate that,
if families do not receive help, they might be more reluctant
to acknowledge the child’s conduct problems. By contrast,
if families do receive help, parents might be more inclined
to report their child’s misbehavior at assessments after
termination of the intervention. It is of interest to
investigate whether effects on parent-rated child behavior
will emerge later on. In order to investigate these ‘sleeper
effects’, long-term follow up assessments are required.
Another informant which is often used in intervention
studies is the teacher. In the present study, teacher ratings
were not taken into account, due to the fact that it is
mandatory for children to attend school from the age of five
onwards in the Netherlands. Most children start attending
school at age four. In the present sample, some children were
younger than four and most children attended school for only
2 or 3 months at PRE. According to our clinical experience,
teachers are often reluctant in reporting behavior problems in
4-year-old children during these first months at school;
therefore we did not include teacher reports.
Mediation in BPT research often is examined by studying
associationsbetweenanimprovementinparentingskillsanda
decrease in children’s problem behavior at the same time.
However, to demonstrate that the improvement in parenting
skills indeed caused the decrease of problem behavior, the
former must be assessed prior to the latter (Kazdin and Nock
2003). We are aware of only one study in which this
sequential pattern of changes was demonstrated (DeGarmo et
al. 2004). Results of the present study demonstrate an
association between improvements in observed parenting
during the intervention, and a change of observed child
.44**
.03
.01
.14
.06 .14
.20
.38*
.15
.12
.11
.41**
- .42*
.51 **
.39 *
- .40 **
Critical statements
PRE
Critical statements
POST
Critical statements
FU1
Critical statements
FU2
Conduct problems
PRE
Conduct problems
POST
Conduct problems
FU1
Conduct problems
FU2
.47**
* p < .05
** p < . 001
Fig. 3 Bidirectional influences of critical statements and child conduct problems
Table 4 Standardized effects of differences between IG and CG
Conduct Problems (DV)
POSTFU1 FU2
Critical Statements
POST
Direct
Indirect
Total
FU1
Direct
Indirect
Total
FU2
Direct
Indirect
Total
0.315
0.000
0.316
0.114
0.099
0.213
0.000
0.269
0.269
0.000
0.000
0.000
0.140
0.000
0.140
0.408
0.063
0.471
0.000
0.000
0.000
Critical Statements (DV)
POST
0.000
0.000
0.000
0.055
0.000
0.055
FU1 FU2
Conduct Problems
POST
Direct
Indirect
Total
FU1
Direct
Indirect
Total
0.000
0.000
0.000
0.153
0.000
0.153
0.000
0.019
0.019
0.000
0.000
0.000
0.000
0.000
0.000
0.106
0.000
0.106
J Abnorm Child Psychol (2012) 40:487–500 497

Page 12

behavior over time. Specifically, evidence for a mediating
effectofthedecreaseofcriticalparentingonthedecreaseofthe
child’s conduct problems was found. This result is in line with
the coercive theory of Patterson (1982), which states that a
sequence of interactions based on negative reinforcement
maintains aggressive behavior problems in children. This
sequence starts with a parent acting aversively towards the
child. The child reacts aversively to the parent, and the parent
gives in. The child’s behavior is thus reinforced and is likely
to increase in the future. Although, in contrast to Patterson
(1982), the direct influence of the parents’ critical statements
on the child’s conduct problems was not assessed during the
observation, the association of the decrease of parental critical
remarks from PRE to POST with the decrease of conduct
problems from PRE to FU2 is in line with the coercive
theory. Furthermore, from the model in which bidirectional
influences of parent and child behavior were investigated, it
became clear that over time parents gained influence over
their child’s behavior; the association of using less critical
statements by parents with the decrease of child’s negative
behavior increased over time, while the influence of child
behavior on the parental use of criticism remained weak over
time. Thus, parents learned to take the lead, which supports
mediation processes occurring during the intervention.
The results of this study have to be considered in the light
of a number of limitations. First, this study was not a
randomized controlled trial. Although matching can be a
viable alternative when randomization is not feasible because
ofgeographicalreasons,itstilllackstheopportunitytocontrol
for unobserved variables that might have influenced the
results. Specifically, this may have resulted in the inclusion of
an IG in which parents were more motivated than parents in
the CGdue toa higherleveloftheir child's conduct problems.
Indeed, although according to the parents the IG and CG did
not differ in problem behavior (CBCL Aggressive Behavior),
the level of observed child's conduct problems was signif-
icantly higher in the IG than in the CG.
Second, although a relatively low inclusion criterion (the
80th percentile on the CBCL aggressive behavior scale)
was used in this study, the mean percentile of the aggressive
behavior scale was 93, indicating the selection of a group of
children at risk for conduct disorders. Nevertheless, it is
possible that we included a number of false positives
(Offord and Bennett 2002), and this may have been one of
the factors that affected the intervention effect (Hill et al.
2004). Accurate identification of children at risk for the
development of a chronic pattern of conduct problems is
essential for effective prevention interventions, but ex-
tremely difficult to obtain (Hill et al. 2004).
Third, the enrollment rate in the intervention group was
relatively low. This might be due to the inclusion criterion
(80th percentile), but even more by the place of recruitment
of the families. Enrollment rates are higher in Incredible
Years studies with a high inclusion threshold, e.g., 77% in a
study with the 95th percentile CBCL score as inclusion
criterion (Barrera et al. 2002) and 24% in a study in which
the inclusion criterion was a score above the median of the
ECBI (Patterson et al. 2002). However, in the latter study
families were recruited in general practices while in four
other studies with high enrollment rates families were
recruited at schools (August et al. 2001; Barrera et al. 2002;
Reid et al. 2007; Scott et al. 2010). Recruitment of families
at schools probably makes participation in a program easier
for parents. Parents, for example, are invited to coffee
mornings to learn about the study and the parenting
program (Scott et al. 2010). When families from one class
are invited to participate because of a relatively high
behavior problem score of their child, as a group they are
probably more inclined to participate than when they would
have been invited separately as was the case in the present
study.
Fourth, our results might have been biased by the high
educational level of the parents who participated in the
present study. Therefore, these findings have limited
generalizability to lower educated parents. Finally, since
the outcome measures used in the present study lack clear
cut off points for clinical levels of functioning, it is not
possible to draw conclusions about the clinical significance
of the findings.
The present study provides evidence for improvements
in parenting skills and observed child behavior resulting
from the IY parent program used as an indicated preventive
intervention. We showed a mediating effect of critical
parenting on the child’s conduct problems and it appeared
that parental influence on child problems behavior in-
creased over time. Although families participating in this
study were followed for 2 years, we cannot draw
conclusions with respect to the long-term effects of the IY
parent program as a preventive intervention yet. Since the
present study showed sustained effects on observed conduct
problems at 2 year follow up and a mediation effect of
parenting skills on the child’s misbehavior, we regard the
IY parent program as a promising intervention for the
prevention of conduct disorders. However, follow up
assessments in middle childhood and adolescence are
needed.
Acknowledgements
participated in this study. We thank Karlijn Steggehuis, Marte van der
Horst and Nienke Willering for delivering the parent groups and for
conducting part of the home visits. We thank Ben van Hout for his
contribution to the design of this study. The original research project
was funded by ZonMw Prevention (#2620.0001).
We are grateful to the parents and children who
Open Access
Creative Commons Attribution Noncommercial License which
permits any noncommercial use, distribution, and reproduction in
any medium, provided the original author(s) and source are credited.
This article is distributed under the terms of the
498J Abnorm Child Psychol (2012) 40:487–500

Page 13

References
Achenbach, T. M., & Rescorla, L. A. (2000). Manual for the ASEBA
preschool forms and profiles. Burlington, VT: University of
Vermont, Research Center for Children, Youth & Families.
Aspland, H., & Gardner, F. (2003). Observational measures of parent-
child interaction: an introductory review. Child and Adolescent
Mental Health, 8, 136–143.
August, G. J., Realmuto, G. M., Hektner, J. M., & Bloomquist, M. L.
(2001). An integrated components preventive intervention for
aggressive elementary school children: the early risers program.
Journal of Consulting and Clinical Psychology, 69, 614–626.
Baron, R. M., & Kenny, D. A. (1986). The moderator-mediator
variable distinction in social psychological research: conceptual,
strategic and statistical considerations. Journal of Personality
and Social Psychology, 51, 1173–1182.
Barrera, M., Biglan, A., Taylor, T. K., Gunn, B. K., Smolkowski, K.,
Black, C., et al. (2002). Early elementary school intervention to
reduce conduct problems: a randomized trial with Hispanic and
non-Hispanic children. Prevention Science, 3, 83–94.
Bellg, A. J., Borrelli, B., Resnick, B., Hecht, J., Minicucci, D. S., Ory,
O., et al. (2004). Enhancing treatment fidelity in health behavior
change studies: best practices and recommendations from the
NIH Behavior Change Consortium. Health Psychology, 23, 443–
451.
Boggs, S. R., Eyberg, S. M., & Reynolds, L. A. (1990). Concurrent
validity of the Eyberg Child Behavior Inventory. Journal of
Clinical Child Psychology, 19, 75–78.
Brotman, L. M., Gouley, K. K., Huang, K., Rosenfelt, A., O’Neal, C.,
Klein, R. G., et al. (2008). Preventive intervention for pre-
schoolers at high risk for antisocial behavior: long term effects on
child physical aggression and parenting practices. Journal of
Clinical Child and Adolescent Psychology, 37, 386–396.
Brotman, L. M., O’Neal, C. R., Huang, K. Y., Gouley, K. K.,
Rosenfelt, A., & Shrout, P. E. (2009). An experimental test of
parenting practices as a mediator of early childhood physical
aggression. Journal of Child Psychology and Psychiatry, 50,
235–245.
Coté, S. M., Vaillancourt, T., LeBlanc, J. C., Nagin, D. S., &
Tremblay, R. E. (2006). The development of physical aggression
from toddlerhood to pre-adolescence: a nationwide longitudinal
study of Canadian children. Journal of Abnormal Child Psychol-
ogy, 34, 71–85.
DeGarmo, D. S., Patterson, G. R., & Forgatch, M. S. (2004). How do
outcomes in a specified parent training intervention maintain or
wane over time? Prevention Science, 5, 73–89.
Dutra, L., Campbell, L., & Westen, D. (2004). Quantifying clinical
judgment in the assessment of adolescent psychopathology: reliabil-
ity, validity, and factor structure of the Child Behavior Checklist for
clinician report. Journal of Clinical Psychology, 60, 65–85.
Eddy, J. M., Dishion, T. J., & Stoolmiller, M. (1998). The analysis of
change in children and families: methodological and conceptual
issues embedded in intervention studies. Journal of Abnormal
Child Psychology, 26, 53–69.
Eyberg, S. M., & Pincus, D. (1999). Eyberg child behavior inventory
& sutter-eybergstudentbehaviorinventory – revised.Psychological
Assessment Resources. Odessa, FL: Psychological Assessment
Resources.
Eyberg, S. M., & Robinson, E. A. (1981). Dyadic parent–child
interaction coding system: A manual. Unpublished Manuscript.
Portland: Oregon Health Sciences University
Farrington, D. P. (2005). Childhood origins of antisocial behavior.
Clinical Psychology and Psychotherapy, 12, 177–190.
Frick, P. J., & Loney, B. R. (2000). The use of laboratory and
performance-based measures in the assessment of children and
adolescents with conduct disorders. Journal of Clinical Child
Psychology, 29, 540–554.
Gardner, F., Burton, J., & Klimes, I. (2006). Randomised controlled
trial of a parenting intervention in the voluntary sector for
reducing child conduct problems: Outcomes and mechanisms of
change. Journal of Child Psychology and Psychiatry, 47, 1123–
1132.
Glasnapp, D. R. (1984). Change scores and regression suppressor
conditions. Educational and Psychological Measurement, 44,
851–867.
Hill, L. G., Lochman, J. E., Coie, J. D., Greenberg, M. T., & The
Conduct Problems Prevention Research Group. (2004). Effec-
tiveness of early screening for externalizing problems: issues of
screening accuracy and utility. Journal of Consulting and
Clinical Psychology, 72, 809–820.
Hutchings, J., Bywater, T., Daley, D., Gardner, F., Whitaker, C., Jones,
K., et al. (2007). Parenting intervention in Sure Start services for
children at risk of developing conduct disorder: pragmatic
randomised trial. British Medical Journal, 334, 678–685.
Kazdin, A. E., & Nock, M. K. (2003). Delineating mechanisms of
change in child and adolescent therapy: methodological issues
and research recommendations. Journal of Child Psychology and
Psychiatry, 44, 1116–1129.
Kazdin, A. E., & Weisz, J. R. (Eds.). (2003). Evidence-based
psychotherapies for children and adolescents. New York:
Guilford Press.
Kim-Cohen, J., Caspi, A., Moffitt, T. E., Harrington, H., Milne, B. J.,
& Poulton, R. (2003). Prior juvenile diagnoses in adults with
mental disorder: developmental follow-back of a prospective-
longitudinal cohort. Archives of General Psychiatry, 60, 709–
717.
Kratochwill, T. R., Elliott, S. N., Loitz, P. A., Sladeczek, I., & Carlson,
J. S. (2003). Cojoint consultation using a self-administered
manual and videotape parent-teacher training: effects on child-
ren’s behavioral difficulties. School Psychology Quarterly, 18,
269–302.
Luk, E. S. L., Staiger, P. K., Mathai, J., Wong, L., Birleson, P., &
Adler, R. (2001). Children with persistent conduct problems who
dropout of treatment. European Child & Adolescent Psychiatry,
10, 28–36.
Maughan, B., & Rutter, M. (2001). Antisocial children grown up. In J.
Hill & B. Maughan (Eds.), Conduct disorders in childhood and
adolescence (pp. 507–552). Cambridge: Cambridge University
Press.
McCart, M. R., Priester, P. E., Davies, W. B., & Azen, R.
(2006). Differential effectiveness of behavioral parent train-
ing and cognitive-behavioral therapy for antisocial youth: a
meta-analysis. Journal of Abnormal Child Psychology, 34,
527–543.
Offord, D. R., & Bennett, K. J. (2002). Prevention. In M. Rutter & E.
Taylor (Eds.), Child and adolescent psychiatry (pp. 881–899).
Oxford: Blackwell.
Patterson, G. R. (1982). Coercive family process. Eugene, OR:
Castilia.
Patterson, J., Barlow, J., Mockford, C., Klimes, I., Pyper, C., &
Stewart-Brown, S. (2002). Improving mental health through
parenting programmes: block randomized controlled trial.
Archives of Disease in Childhood, 87, 472–477.
Raaijmakers, M., Koffijberg, H., Posthumus, J., Van Hout, B., Van
Engeland, H., & Matthys, W. (2008). Assessing the performance
of a randomized versus a non-randomized study design.
Contemporary Clinical Trials, 29, 293–303.
Raaijmakers, M. A., Posthumus, J. A., Van Hout, B. A., Van
Engeland, H., & Matthys, W. (2011). Cross-sectional study into
the costs and impact on family functioning of 4-year-old children
with aggressive behavior. Prevention Science, 12, 192–200.
J Abnorm Child Psychol (2012) 40:487–500499

Page 14

Reid, M. J., Webster-Stratton, C., & Hammond, M. (2007). Enhancing
a classroom social competence and problem solving curriculum
by offering parent training to families of moderate to high-risk
elementary school children. Journal of Clinical Child and
Adolescent Psychology, 36, 605–620.
Rich, B. A., & Eyberg, S. M. (2001). Accuracy of assessment: the
discriminative and predictive power of the Eyberg Child
Behavior Inventory. Ambulatory Child Health, 7, 249–257.
Robinson, E. A., & Eyberg, S. M. (1981). The dyadic parent-child
interaction coding system: standardization and validation. Journal
of Consulting and Clinical Psychology, 49, 245–250.
Scott, S., Knapp, M., Henderson, J., & Maughan, B. (2001a).
Financial costs of social exclusion: follow-up study of antisocial
children into adulthood. British Medical Journal, 323, 191–194.
Scott, S., Spender, Q., Doolan, M., Jacobs, B., & Aspland, H. (2001b).
Multicentre controlled trial of parenting groups for childhood
antisocial behaviour in clinical practice. British Medical Journal,
323, 1–7.
Scott, S., O’Connor, T. G., Futh, A., Matias, C., Price, J., & Doolan,
M. (2010). Impact of a parenting program in a high risk, multi-
ethnic community: the PALS trial. Journal of Child Psychology
and Psychiatry, 51, 1331–1341.
Shaw, D. S., Lacourse, E., & Nagin, D. S. (2005). Developmental
trajectories of conduct problems and hyperactivity from ages 2 to
10. Journal of Child Psychology and Psychiatry, 46, 931–942.
Society for Prevention Research (2005). Standards of evidence:
Criteria for efficacy, effectiveness and dissemination. http://
www.preventionresearch.org
Taylor, T. K., Schmidt, F., Pepler, D., & Hodgins, H. (1998). A
comparison of eclectic treatment with Webster-Stratton’s Parents
and Children Series in a Children’s Mental Health Center: A
randomized controlled trial. Behavior Therapy, 29, 221–240.
Tremblay, R. E., Nagin, D. S., Séguin, J. R., Zoccolillo, M., Zelazo, P.
D., Boivin, M., et al. (2004). Physical aggression during
early childhood: trajectories and predictors. Pediatrics, 114,
43–50.
Webster-Stratton, C. (1994). Advancing videotape parent training: a
comparison study. Journal of Consulting and Clinical Psychology,
62, 583–593.
Webster-Stratton, C. (1998). Preventing conduct problems in Head
Start children: strengthening parenting competencies. Journal of
Consulting and Clinical Psychology, 66, 715–730.
Webster-Stratton, C. (2001a). Parenting practices interview. Unpub-
lished assessment instrument. (http://www.son.washington.edu/
centers/parenting-clinic/forms.asp).
Webster-Stratton, C. (2001b). The incredible years: Parents and
children videotape series: A parenting course (BASIC). Seattle,
WA: Incredible Years.
Webster-Stratton, C. (2002). The incredible years: Parents and
children videotape series: A parenting course (ADVANCE).
Seattle, WA: Incredible Years.
Webster-Stratton, C., & Hammond, M. (1997). Treating children with
early-onset conduct problems: a comparison of child and parent
training interventions. Journal of Consulting and Clinical
Psychology, 65, 93–109.
Webster-Stratton, C., & Hancock, L. (1998). Training for parents of
young children with conduct problems: Content, methods, and
therapeutic processes. In C. E. Schaefer & J. M. Briesmeister
(Eds.), Handbook of parent training (pp. 98–152). NY: John
Wiley & Sons.
Webster-Stratton, C., & Taylor, T. (2001). Nipping early risk factors in
the bud: preventing substance abuse, delinquency, and violence
in adolescence through interventions targeted at young children
(0–8 years). Prevention Science, 2, 165–192.
Webster-Stratton, C., Reid, M. J., & Hammond, M. (2001). Preventing
conduct problems, promoting social competence: a parent and
teacher training partnership in Head Start. Journal of Clinical
Child Psychology, 30, 283–302.
Webster-Stratton, C., Reid, M. J., & Hammond, M. (2004). Treating
children with early conduct problems: intervention outcomes for
parent-, child- and teacher training. Journal of Clinical Child and
Adolescent Psychology, 33, 221–239.
500 J Abnorm Child Psychol (2012) 40:487–500