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Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum

Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum

Evidence rating
3
Cost rating
2
Review: January 2021

Note on provider involvement: This provider has agreed to EIF’s terms of reference, and the assessment has been conducted and published with the full cooperation of the programme provider.

Incredible Years ADVANCE is an add-on programme to the Incredible Years Preschool BASIC and School Age BASIC programmes. It is designed to be delivered to families after they have received the BASIC programmes, particularly where child risk factors (oppositional or aggressive behaviours, ADHD, poor social skills or autism spectrum disorders) or parent risk factors (mental health problems, poor communication skills, social isolation, marital conflict or emotion regulation difficulties) are present.

This Guidebook page describes Incredible Years ADVANCE, when delivered as an add-on to the Preschool BASIC programme (which has its own standalone Guidebook entry here).

The Preschool BASIC programme is a targeted indicated parenting programme for parents of children between the ages of 3 and 6 diagnosed with oppositional-defiant or conduct disorder. It is delivered in communal settings (children’s centres, primary schools, community centres, outpatient settings) and aims to improve parents’ communication skills as well as children’s emotion regulation, cooperation, problem-solving skills, relational skills and academic learning.

The ADVANCE programme involves adding 9–12 sessions of 2–2.5 hours’ duration each to the BASIC programme. Incredible Years recommend adding the ADVANCE programme for high-risk groups as these tend to progress slower through the curriculum content. Adding the ADVANCE programme enables parents and practitioners to consolidate covered content and progress on content for which there was no time in the BASIC programme sessions.

Incredible Years Preschool BASIC + ADVANCE targets parents’ skills in the areas of communication, emotion regulation, problem-solving, relationship building and parenting in order to achieve positive outcomes for children in these areas and regarding academic progress. The ADVANCE components offer practitioners the opportunity to strengthen and reinforce topics already covered in the BASIC programme component as well as introduce new topics. It is recommended for higher-risk groups to consolidate learning effects.

Parents learn through discussion, home assignments, video vignettes, roleplay practices and individual goal-setting. Therapists use a collaborative process to encourage discussion in which parents self-reflect and develop parent principles that help them generalise the material presented to their own parenting situations. Roleplay practice provides opportunities for therapists to help individualise scenarios to the parents own situations and then to practise skills. This behavioural practice is then continued at home through structured home activities that parents complete and discuss the following week. While the programme is structured and has a manual and required material to cover, the model is built on the principle of tailoring the topics, activities and skills to the individual families in the group.

This programme seeks, in part, to improve children's outcomes by improving the quality of interparental relationships (IPR).

EIF Programme Assessment

Evidence rating
3

Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum has evidence of a short-term positive impact on child outcomes from at least one rigorous evaluation.

What does the evidence rating mean?

Level 3 indicates evidence of efficacy. This means the programme can be described as evidence-based: it has evidence from at least one rigorously conducted RCT or QED demonstrating a statistically significant positive impact on at least one child outcome.

This programme does not receive a rating of 4 as it has not yet replicated its results in another rigorously conducted study, where at least one study indicates long-term impacts, and at least one uses measures independent of study participants. 

What does the plus mean?

The plus rating indicates that this programme has evidence from at least one level 3 study, along with evidence from other studies rated 2 or better.

Please note that Incredible Years ADVANCE is designed as an add-on to the Incredible Years BASIC programmes. However, there is only one study available comparing Incredible Years Preschool BASIC (the standard programme version without the ADVANCE components) with Incredible Years Preschool BASIC plus ADVANCE. The majority of the evidence included in this assessment compares the outcomes of families receiving Incredible Years Preschool BASIC combined with the ADVANCE programme, to families receiving neither. Consequently, while this evidence suggests improvements for families receiving Incredible Years Preschool BASIC + ADVANCE compared to those receiving no treatment, this evidence cannot tell us that the ADVANCE component is adding value over and above the BASIC programme (i.e., that those receiving ADVANCE in addition to BASIC have better outcomes than families who only receive the BASIC programme). The one study that does examine the 'value-add' of IY ADVANCE is study 4 (Webster-Stratton, 1994). This study compares parents participating in the Preschool BASIC programme only with those receiving the Preschool BASIC and ADVANCE programme. This suggests improvements over the BASIC programme in terms of parents’ problem-solving and communication skills: 72% of ADVANCE mothers and 73% of ADVANCE fathers showed an increase in problem-solving and communication skills of clinical significance, contrasted with only 33% of BASIC mothers and 29% of BASIC fathers. In terms of child outcomes, children in the ADVANCE condition improved their social problem-solving skills whereas children in the BASIC condition did not improve on this outcome. Parent-reported child behaviour or observed interactions between children and parents did not differ between the groups.

Cost rating
2

A rating of 2 indicates that a programme has a medium-low cost to set up and deliver, compared with other interventions reviewed by EIF. This is equivalent to an estimated unit cost of £100–£499.

Child outcomes

According to the best available evidence for this programme's impact, it can achieve the following positive outcomes for children:

Supporting children's mental health and wellbeing

based on

Preventing crime, violence and antisocial behaviour

based on
11.32-point improvement on a child conduct problems at home composite score (including the Eyberg Child Behaviour Inventory, the Coders Impressions Inventory for Children, and the Dyadic Parent-Child Interaction Coding System)
Improvement index: +25
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 75% and worse outcomes than 25% of their peers, if they had received the intervention.
Immediately after the intervention
8.42-point improvement on a child conduct problems at home composite score (including the Eyberg Child Behaviour Inventory, the Coders Impressions Inventory for Children, and the Dyadic Parent-Child Interaction Coding System)
Improvement index: +24
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 74% and worse outcomes than 26% of their peers, if they had received the intervention.
Immediately after the intervention
based on
based on
based on
10.41-point improvement on the Child Behaviour Checklist (Total behaviour problems – mother report)
Improvement index: +39
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 89% and worse outcomes than 11% of their peers, if they had received the intervention.
Immediately after the intervention
36.84-point improvement on the Eyberg Child Behaviour Inventory (Intensity scale - mother report)
Improvement index: +40
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 90% and worse outcomes than 10% of their peers, if they had received the intervention.
Immediately after the intervention
23.03-point improvement on the Parent Stress Index (Child Domain Score - mother report)
Improvement index: +37
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 87% and worse outcomes than 13% of their peers, if they had received the intervention.
Immediately after the intervention
based on
based on
4.18-point improvement on the Parent Daily Report (Number of Target Negative Behaviours - mother report)
Improvement index: +43
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 93% and worse outcomes than 7% of their peers, if they had received the intervention.
Immediately after the intervention
1.84-point improvement on the Parent Daily Report (Number of negative behaviours per 24 hours - mother reports)
Improvement index: +23
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 73% and worse outcomes than 27% of their peers, if they had received the intervention.
Immediately after the intervention
based on
2.06-point improvement on the Parent Daily Report (Number of Target Positive Behaviours - mother report)
Improvement index: +17
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 67% and worse outcomes than 33% of their peers, if they had received the intervention.
Immediately after the intervention
2.88-point improvement on the Parent Daily Report (Number of positive behaviours per 24 hours - mother report)
Improvement index: +31
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 81% and worse outcomes than 19% of their peers, if they had received the intervention.
Immediately after the intervention
based on
4.09-point improvement on the Peer Problem-Solving-Interaction Communication-Affect Rating Coding System (total negative conflict management)
Improvement index: +23
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 73% and worse outcomes than 27% of their peers, if they had received the intervention.
Immediately after the intervention
based on
9.06-point improvement on the Dyadic Parent-Child Interactive Coding System-Revised
Improvement index: +25
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 75% and worse outcomes than 25% of their peers, if they had received the intervention.
Immediately after the intervention

This programme also has evidence of supporting positive outcomes for couples, parents or families that may be relevant to a commissioning decision. Please see About the evidence for more detail.

Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum

Key programme characteristics

Who is it for?

The best available evidence for this programme relates to the following age-groups:

  • Preschool
  • Primary school

How is it delivered?

The best available evidence for this programme relates to implementation through these delivery models:

  • Group

Where is it delivered?

The best available evidence for this programme relates to its implementation in these settings:

  • Children's centre or early-years setting
  • Primary school
  • Community centre
  • Out-patient health setting

How is it targeted?

The best available evidence for this programme relates to its implementation as:

  • Targeted indicated

Please note: This programme has also been delivered as targeted selective (preventive) intervention (see study 3, Posthumus et al., 2012).

Where has it been implemented?

England, Estonia, Netherlands, Russia, United States, Wales, Ireland

UK provision

This programme has been implemented in the UK.

UK evaluation

This programme’s best evidence does not include evaluation conducted in the UK.

Spotlight sets

EIF includes this programme in the following Spotlight sets:

  • Improving interparental relationships
  • Parenting programmes with violence reduction outcomes
  • Programmes for children with recognised or possible special education needs
Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum

About the programme

What happens during delivery?

How is it delivered?

  • Incredible Years Preschool BASIC is delivered in 12–16 sessions of 2 hours’ duration each by two practitioners to 5–8 families.  

  • For Incredible Years ADVANCE, an additional 9–12 sessions of 2–2.5 hours’ duration each are delivered by two practitioners, to groups of 5–8 families (8–12 parents).  

What happens during the intervention?
  • Parents learn through discussion, home assignments, video vignettes, roleplay practices, and individual goal-setting.
  • Video vignettes provide models of effective communication, emotion regulation and problem-solving strategies for parents to discuss and apply to their own lives. There are also less effective video models that are catalysts for parents to discuss what they would do differently. Therapists use a collaborative process to encourage discussion in which parents self-reflect and develop parent principles that help them generalise the material presented to their own parenting situations.
  • Roleplay practice provides opportunities for therapists to help individualise scenarios to the parents’ own situations and then to practise skills.
  • This behavioural practice is then continued at home through structured home activities that parents complete and discuss the following week. While the programme is structured and has a manual and required material to cover, the model is also built on the principle of tailoring the topics, activities, and skills to the individual families in the group.

What are the implementation requirements?

Who can deliver it?
  • The practitioners who deliver this programme are two psychologists, mental health counsellors, marriage and family therapists, social workers or similar practitioners with QCF-7/8 level qualifications. 
What are the training requirements?
  • Both practitioners have 18 hours of programme training for the Incredible Years BASIC programme plus 16 hours of programme training for the Incredible Years ADVANCE programme. Booster training of practitioners is recommended. 
How are the practitioners supervised?

Practitioner supervision is provided through the following processes: 

  • It is recommended that practitioners are supervised by one clinical host agency supervisor (qualified to QCF-7/8 level), with 2–3 years of programme training.   

What are the systems for maintaining fidelity?

Programme fidelity is maintained through the following processes: 

  • Training manual 

  • Other printed material 

  • Other online material 

  • Video or DVD training 

  • Face-to-face training 

  • Fidelity monitoring 

Is there a licensing requirement?

There is no licence required to run this programme.

How does it work? (Theory of Change)

How does it work?

  • Parents model social behaviour for their children. Their affect, communication, and conflict resolution skills influence children’s conduct problems.  

  • Incredible Years Preschool BASIC plus ADVANCE aims to improve protective factors (parental communication skills, parental emotion and mood regulation, parental problem-solving skills and support networks including partner relationship and parent–teacher partnerships) in order to enhance parents’ ability to parent effectively, to model and regulate their own emotions, and to teach emotion regulation and problem-solving skills to their children.  

  • Parents learn to effectively problem-solve and communicate with parenting partners, teachers and their children; and to give and get support from others. This in turn leads to positive outcomes for children in the areas of child emotion regulation, compliance/cooperation, problem-solving skills, positive relationships with peers and academic learning.  

  • In the long term this leads to reductions in behaviour problems, academic failure, school drop-out, depression, violence and substance abuse. 

Intended outcomes

Supporting children's mental health and wellbeing
Enhancing school achievement & employment
Preventing crime, violence and antisocial behaviour
Preventing substance abuse

Contact details

Incredible Years Preschool BASIC + ADVANCE Parent Training Curriculum

About the evidence

Incredible Years Preschool BASIC + ADVANCED’s most rigorous evidence comes from two RCTs which were conducted in the US.  

Both studies identified statistically significant positive impact on a number of child and parent outcomes. 

This programme has evidence from two rigorously conducted RCTs. Consequently, the programme receives a 3+ rating overall. 

Study 1

Citation: Webster-Stratton et al. (2004)
Design: RCT
Country: United States
Sample: 159 families, with children between 4 and 8 years old (on average 5.9 years old), where the child met DSM-IV criteria for oppressive-defiant disorder and the child was enrolled in preschool or elementary school.
Timing: Post-test
Child outcomes: Improved behaviour at home
Other outcomes: Reduced negative parenting (mothers and fathers)
Improved positive parenting (mothers and fathers)
Study rating: 3

Webster-Stratton, C., Reid, M. J., & Hammond, M. (2004). Treating Children With Early-Onset Conduct Problems: Intervention Outcomes for Parent, Child, and Teacher Training. Journal of Clinical Child and Adolescent Psychology, 33(1), 105-124.  

Available at 
https://pubmed.ncbi.nlm.nih.gov/15028546/  

Study design and sample 

This study is a rigorously conducted RCT.   

This study involved random assignment of children to one of six groups:  

  • parent training (Incredible Years Preschool BASIC+ADVANCE),  
  • parent plus teacher training,  
  • child training (Incredible Years Dinosaur School),  
  • child plus teacher training,  
  • parent, child and teacher training 
  • control group.  

This study was conducted in the U.S., with a sample of children aged between 4 and 8 (average age 5.9 years). Thirty-one families participated in the parent training group. Most children were male (90.3%) and White (71%).   

Measures 

Child conduct problems at home were measured using a composite score consisting of the Eyberg Child Behaviour Inventory (parent report), the Dyadic Parent-Child Interaction Coding System (expert observation of behaviour), and the CII-Parenting Style (expert observation of behaviour). 

Child conduct problems at school and with peers were measured using a composite score consisting of the Teacher Assessment of School Behaviour (teacher report), the Perceived Competence Scale for Young Children (teacher report), MOOSES classroom observation system (expert observation of behaviour), Social Health Profile (expert observation of behaviour), and the Dyadic Peer Interaction scale (expert observation of behaviour). 

Child social competence with peers was measured using a composite score consisting of the Teacher Assessment of School Behaviour (teacher report), Social Health Profile (expert observation of behaviour), and the Dyadic Peer Interaction scale (expert observation of behaviour).  

Findings 

This study identified statistically significant positive impact on a number of child and parent outcomes. 

This includes reduced child conduct problems at home (composite score).  

More Less about study 1

Study 2

Citation: Webster-Stratton & Hammond (1997)
Design: RCT
Country: United States
Sample: 26 families, with children between 4 and 7 years old (mean age 64 months), mostly boys (81%) where families are mainly Caucasian (85%), mostly married (62%), and spread relatively evenly across the income spectrum.
Timing: Post-test; 1-year follow up (control group lost to follow up)
Child outcomes: Improved child behaviour
Reduced negative behaviours
Improved positive behaviour
Improved peer interactions
Increased positive affect in children's interactions with fathers
Other outcomes: Reduced commands and criticisms (mother only)
Increased praise (mother and father)
Increased positive affect with child (mother and father)
Decreased negative valence with child (mother and father)
Reduced spanking (mother only, father not measured)
Study rating: 3

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(1), 93-109.  

Available at
https://www.incredibleyears.com/article/treating-children-with-early-onset-conduct-problems-a-comparison-of-child-and-parent-training-interventions/ 

Study design and sample 

This study is a rigorously conducted RCT.   

This study involved random assignment of children to one of four groups:  

  • Parent training (Incredible Years Preschool BASIC + ADVANCE) 
  • Child training (Incredible Years Dinosaur School) 
  • Parent and child training 
  • Control group (lost to 1-year follow up).  

This study was conducted in the U.S. with a sample of 97 families with children aged between 4 and 7 years old (mean age 6). The overall sample was mainly White (86%) with children in the clinical range of child conduct problems before treatment began. Families were spread evenly across the income spectrum.  

Measures 

Child conduct problems were measured using the Child-Behaviour Checklist (parent report), the Eyberg Child Behaviour Inventory (parent report), and Parent Daily Reports (parent report).  

Children’s social problem-solving skills were measured using the Wally Child Social Problem-Solving Detective Game (expert observation of behaviour).  

Child behaviour at home was measured using the Dyadic Parent-Child Interaction Coding System (expert observation of behaviour).  

Child conduct problems at school were measured using the Behar Preschool Questionnaire (teacher report).  

Children’s problem-solving skills with peers were measured using the Peer Problem-Solving-Interaction Communication-Affect Rating Coding System (expert observation of behaviour).  

Findings 

This study identified statistically significant positive impact on a number of child and parent outcomes. 

This includes reductions in child conduct problems, improvements in child behaviour at home, and improvements in children’s problem solving skills.   

More Less about study 2

Study 3

Citation: Posthumus et al. (2012)
Design: QED
Country: Netherlands
Sample: 144 families, with children aged 4 years, where children’s behaviour is particularly aggressive. Parents were relatively well educated and mainly Caucasian.
Timing: Post-test; 1-year follow up; 2-year follow up
Child outcomes: Improved behaviour at home
Other outcomes: Improved appropriate discipline (disciplining children when they misbehave)
Reduced harsh, inconsistent discipline (e.g., threatening but not punishing)
Increased parents' use of praise and incentives
Study rating: 2

Posthumus, J. A., Raaijmakers, M. A. J., Maassen, G. H., van Engeland, H., & Matthys, W. (2012). Sustained Effects of Incredible Years as a Preventive Intervention in Preschool Children with Conduct Problems. Journal of Abnormal Child Psychology, 40, 487-500.  

Available at 
https://pubmed.ncbi.nlm.nih.gov/22006348/  

Study design and sample 

This study is a QED.   

503 families were invited to take part in the intervention and assigned to intervention or control group based on their place of residence. The study reports findings on 144 families matched on the child’s gender, level of aggression, IQ, and the parents’ educational level, stress level, and address density of the place of residence of the family.  

This study was conducted in the Netherlands, with a sample of children age 4. Families were predominantly Caucasian and were evenly spread across education levels.  

Measures 

Child behaviour was measured using the Eyberg Child Behaviour Inventory (parent report) and the Dyadic Parent-Child Interaction Coding System-Revised (expert observation of behaviour). 

Parenting behaviour was measured using the Dyadic Parent-Child Interaction Coding System-Revised (expert observation of behaviour) and the Parent Practices Interview (self report). 

Findings 

This study identified statistically significant positive impact on a number of child and parent outcomes. 

This includes improved child and parenting behaviour.  

The conclusions that can be drawn from this study are limited by methodological issues pertaining to the treatment and comparison groups not being generated by sufficiently robust methods and high attrition, hence why a higher rating is not achieved. 

More Less about study 3

Study 4

Citation: Webster-Stratton (1994)
Design: RCT
Country: United States
Sample: 77 families, with children between 3 and 8 years old (mean age 58.72 months), where children are diagnosed with oppositional defiant disorder or conduct and families experience high levels of adversity.
Timing: Interim measurement after both groups completed BASIC treatment; Post-test
Child outcomes: Improved social problem-solving
Improved child behaviour
Improved behaviour at home
Other outcomes: Reduced depression
Reduced parent stress
Reduced anger (mothers only)
Improved problem solving
Study rating: 2

Webster-Stratton, C. (1994). Advancing Videotape Parent Training: A Comparison Study. Journal of Consulting and Clinical Psychology, 62(3), 583-593.  

Available at
https://www.incredibleyears.com/article/advancing-videotape-parent-training-a-comparison-study/ 

Study design and sample 

This study is an RCT.   

This study involved random assignment of children to an Incredible Years Preschool BASIC group and an Incredible Years Preschool BASIC plus ADVANCE group.    

This study was conducted in the U.S., with a sample of children aged between 3 and 8 years where children meet the DSM-III criteria for oppositional defiant disorder or conduct disorder but had no debilitating physical impairment, intellectual deficit, or history of psychosis and receive no treatment at time of referral. Most parents were married (69%), have a median yearly family income of $35,000 and experience high levels of adversity (domestic abuse, substance misuse, experienced child abuse as children. Ethnicity of attending families was not reported.   

Measures 

Child conduct problems were measured using the Eyberg Child Behaviour Inventory (parent report) and the Child Behaviour Checklist (parent report). 

Child social competence was measured using the Child Behaviour Checklist.  

Child deviance and noncompliance were measured using the Dyadic Parent-Child Interaction Coding System (expert observation of behaviour).

Child social problem-solving skills were measured using the Child Social Problem-Solving Test Revised (expert observation of behaviour).  

Findings 

This study identified statistically significant positive impact on a number of child and parent outcomes. 

This includes reduced child conduct problems, improved child social competence, and reduced child deviance and noncompliance. Only the ADVANCE group showed improved social problem-solving skills.  

The conclusions that can be drawn from this study are limited by methodological issues pertaining to unequivalent groups and high attrition, hence why a higher rating is not achieved. 

More Less about study 4

Other studies

The following studies were identified for this programme but did not count towards the programme's overall evidence rating. A programme receives the same rating as its most robust study or studies.

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(3), 283-302 - This reference refers to a randomised control trial, conducted in the USA.

Brotman, L. M., Gouley, K. K., Huang, K.-Y., Rosenfelt, A., O’Neal, C., & Klein, R. G. (2008). Preventive Intervention for Preschoolers at High Risk for Antisocial Behaviour: Long-Term Effects on Child Physical Aggression and Parenting Practices. Journal of Clinical Child & Adolescent Psychology, 37(2), 386-396 - This reference refers to a randomised control trial, conducted in the USA.

Brotman, L. M., Klein, R. G., Kamboukos, D., Brown, E. J., Coard, S. I., & Stout Sosinsky, L. (2003). Preventive Intervention for Urban, Low-Income Preschoolers at Familial Risk for Conduct Problems: A Randomized Pilot Study. Journal of Clinical Child and Adolescent Psychology 32(2), 246-257 - This reference refers to a randomised control trial, conducted in the USA.

Webster-Stratton, C. H., & Reid, M. J. (2011). Combining Parent and Child Training for Young Children with ADHD. Journal of Clinical Child & Adolescent Psychology, 40(2), 191-203 - This reference refers to a randomised control trial, conducted in the USA.

Published May 2024

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