Trauma-Informed Mindfulness-Based Yoga

Internalizing and externalizing behaviors will be measured using two subscales from The Child Behavior Checklist - Youth Self-Report (YSR). The YSR (18) is a self-report questionnaire divided in two parts: 1) Competencies and 2) Problems. It consists of 112 problem items covering different symptoms/behaviors each to be rated on a three-point scale (2 indicates that the symptom is present most of the time or applies well, 1 indicates that the symptom is present some of the time or applies to some extent, and 0 indicates the absence of symptom or problem behavior). All ratings refer to symptoms or problems experienced during the preceding 6 months.

Anger will be measured using the 57-item State-Trait Anger Expression Inventory (STAXI-2) which assesses youth's experience with and expression/control of anger. Specifically, the STAXI-2 includes self-report scales that measure State Anger, Trait Anger, Anger Expression-Out, Anger Expression-In, Anger Control-Out, Anger Control-In, and Anger Expression Index. Ratings are on a 4-point forced-choice response scale ("Not at all" to "Almost Always"). The State Anger scale measures transient anger intensity, while the Trait Anger scale measures the frequency of angry feelings. The Anger Expression-In scale measures the extent to which one "holds things in" or suppresses anger, whereas the Anger Expression-Out scale measures the actual expression of aggression. The Anger Control-In scale measures the extent to which the suppression of anger is controlled, whereas the Anger Control-Out scale measures the constraint of overt anger expression.

Trauma-related symptoms will be assessed using the Structured Trauma-Related Experiences and Symptoms Screener (STRESS) which inventories 25 adverse childhood experiences/potentially traumatic events and assesses symptoms of PTSD. The STRESS assesses the four DSM-5 PTSD symptom clusters, dissociative symptoms, and trauma-related functional impairment (i.e., ability to make or keep friends, get along with other kids, do schoolwork, get along with teachers, get along with household, and get chores done) using 21 items measured on a 4-point rating scale (none, 1 day, 2-3 days, and most days). The STRESS uses a briefer retrospective time frame when assessing symptoms based on evidence that children's retrospective report is less valid over an extended period of time (De Los Reyes \& Kazdin, 2005).

Impulsivity will be assessed using the Barratt Impulsiveness Scale (BIS), which is a 30-item 4-point rating scale ("rarely/never" to "almost always/always") and captures 3 domains of impulsivity: cognitive impulsiveness which involves making quick decisions (e.g., "I make up my mind quickly"), motor impulsiveness which involves acting without thinking (e.g., "I act on the spur of the moment"), and non-planning impulsiveness which involve a lack of ''futuring" or forethought (e.g., "I am more interested in the present than the future").

Psychological flexibility will be assessed using the Acceptance and Action Questionnaire (AAQ-II) is the most widely used measure of experiential avoidance and psychological inflexibility. The AAQ-II is a seven-item self-report measure that uses a 7-point Likert scale (1=never true, 7=always true). Sample items include "I am afraid of my feelings" and "Emotions cause problems in my life." Three of the AAQ-II items are taken directly from the nine-item AAQ.

Mindfulness will be assessed using the Cognitive and Affective Mindfulness Scale-Revised (CAMS-R) is a 12-item measure designed to measure four core characteristics of mindfulness described by Kabat-Zinn (1990): (1) the ability to regulate attention ["I have a hard time concentrating on what I am doing," (reverse-scored)], (2) an orientation to present or immediate experience [e.g., "I focus on the present moment", "I am preoccupied with the past" (reverse scored)], (3) awareness of experience (e.g., "It's easy for me to keep track of my thoughts and feelings"), and (4) an attitude of acceptance or nonjudgment towards experience (e.g., "I believe it is OK to be sad or angry"). Participants respond on a 4-point Likert scale from "Rarely/not at all" to "Almost always."