Randomized Controlled Trial of Regulation-Focused Psychotherapy (RFP-C)

Strengths and Difficulties Questionnaire - Parent version (SDQ-P; Goodman, 2001) is a 25-item scale that asks parents to rate their children's emotional and behavioral difficulties on a 3-point Likert scale, ranging from 0 = not true to 2 = very true. The questionnaire is composed of five subscales: Emotional Symptoms, Conduct Problems, Hyperactivity-Inattention, Peer Problems and Prosocial. In addition, the SDQ-P yields Internalizing Difficulties, Externalizing Difficulties and Total Difficulties scale scores. SDQ-P was demonstrated to be a valid and reliable scale for use in Turkish children and adolescents (Yalın et al., 2013).

Turgay DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S; Turgay, 1994) is based on DSM-IV diagnostic criteria and examines hyperactivity/impulsivity, inattention, opposition-defiance, and conduct disorder. Symptoms are scored on a four-point Likert scale (0= not at all, 1= just a little, 2= quite a bit, and 3= very much). T-DSM-IV-S has shown good reliability and validity.

Me and My Feelings Questionnaire (M&MF; Deighton et al., 2013) is a child-report measure consisting of total short 16-items: 10-items of emotional difficulties scale and 6-items of behavioral difficulties scale. It is scored on a 3-point likert scale (0 = "never expressed", 1 = "sometimes expressed", 2 = "always expressed"). Total score of scales are calculated as the sum of item scores with threshold values 10 for the emotional difficulties and six for the behavioral difficulties. Higher scores of each set of difficulties indicate the probability of mental health problems. The scale has been adapted to Turkish with good reliability and validity (İlnem, 2020).

Emotion Regulation Checklist (ERC; Shields & Cicchetti, 1997) is a parent-report measure of children's emotion regulation characteristics and involves 24-items rated on a 5-point likert scale (1 = "never" to 5 = "always"). It taps into two factors one of which is emotional lability and negativity defined as arousal, anger dysregulation, and mood changes; and the second is emotion regulation defined as socially appropriate emotional displays, empathy, and emotional selfawareness. The scale has been adapted to Turkish with good reliability and validity (Batum & Yagmurlu, 2007).

The Emotion Awareness Questionnaire (EAQ-30; Rieffe et al., 2008) aims to identify how children and adolescents feel and think about their feelings. The EAQ (30 items) was designed with a six-factor structure describing six aspects of emotional functioning: (1) Differentiating Emotions, (2) Verbal Sharing of Emotions, (3) Not Hiding Emotions (formerly Acting Out), (4) Bodily Awareness of Emotions, (5) Attending to Others' Emotions, and (6) Analyses of Emotions. Respondents are asked to rate the degree to which each item is true about them on a three-point scale (1 = not true, 2 = sometimes true, 3 = often true). The scale has been adapted to Turkish with good reliability and validity (İnceman, 2017).

The Children's Global Assessment Scale (CGAS; Schaffer et al., 1983) is a numeric scale (from 1 to 100) used by mental health clinicians to rate the global functioning of children under the age of 18 on a scale of 0 to 100. 90- 81 range is scored when there is "good functioning in all areas; security in family, school, and with peers with only transient difficulties and everyday worries"; 50-41, when there is "moderate degree of interference in functioning in most social areas or severe impairment of functioning in one area"; and 20-11, when there is "need for considerable supervision to prevent hurting others or self or to maintain personal hygiene or gross impairment in all forms of communication". The scale has been adapted to Turkish with good reliability and validity (Gökler et al., 2004).

Parental Stress Index - Short Form (PSI-SF; Abidin, 1983) is a 36-item parent-report scale.The PSI-SF contains 36 items divided into three subscales, each composed of 12 items: "Parental distress"; "Parent-child dysfunctional interaction"; "Difficult child". Each item is rated on a 5-point likert scale from 1 = "strongly disagree" to 5 = strongly agree". The PSI-SF gives three subscores and a total distress score. The scale has been adapted to Turkish with good reliability and validity (Ertan et al., 2008).

Difficulties in Emotion Regulation Scale (DERS; Gratz & Roemer, 2004) is an instrument measuring emotion regulation problems in adults (to be used with parents in the current study). The scale comprises 36 items that are rated on a 5- point likert scale from 1 = "almost never" to 5 = "almost always", with higher scores indicating a difficulty of emotion regulation. The scale produces scores on the following subscales: (a) lack of awareness of emotional responses; (b) lack of clarity of emotional responses; (c) nonacceptance of emotional responses; (d) limited access to effective strategies; (e) difficulties in controlling impulsive behavior when experiencing negative affect; and (f) difficulties in engaging goal directed behavior when experiencing negative affect as well as a total disregulation score. The scale has been adapted to Turkish with good reliability and validity (Yiğit & Güzey-Yiğit, 2017).

Adverse Childhood Experiences Scale (ACE; Dube et al., 2004) is a parent-report scale to assess retrospectively forms of abuse, neglect, and household dysfunction (i.e., witnessing domestic violence, separation and mental illness in the family) in the current study. Scores range from 0-10 on the ACE, with the latter representing full exposure at some point in the first 18 years of life, to all forms of household dysfunction and abuse detailed in the questionnaire.It has a parent and a child version. The scale has been adapted to Turkish by Gunduz et al. (2018).

The Therapeutic Alliance Scale for Children-revised (TASC-r; Creed &Kendall, 2005) is a 12-item tool that measures alliance across the three dimensions of task, bond and goals and covers both positive and negative aspects of therapeutic alliance. Each response is rated on a four point Likert scale (i.e. ''not at all like my client'' to ''very much like my client''). It has been found to have adequate reliability and validity in Turkey (Bulut, et al., 2023).

Wechsler Abbreviated Scale of Intelligence (WASI-II; Weschler, 1999) is a brief measure of verbal and nonverbal intelligence administered by trained researchers to parents and children.