The population-based cohort study focusing on immigrant children and their families will use instruments that are well-validated with robust psychometric properties and that have been frequently used in previous research. We will further conduct piloting (pretesting questionnaires) to evaluate the construct validity, factor structure, and other psychometric properties of these instruments, including appropriateness to the specific age-groups. The children’s questionnaire will be carefully evaluated using cognitive testing methods, which enable to detect problematic wordings or questions (De Leeuw ED. Improving data quality when surveying children and adolescents: Cognitive and social development and its role in questionnaire construction and pretesting. 2011). We will evaluate the following instruments to be used in the Disparity-in-Well-being Project:

Child and adolescent instruments (reference in parenthesis):

• KIDSSCREEN-27 instrument assesses subjective measures of the health-related quality of life: physical well-being; psychological well-being; autonomy and parent relations; social support and peers; school environment (Robitail S, Ravens-Sieberer U, Simeoni M-C, et al. Testing the structural and cross-cultural validity of the KIDSCREEN-27 quality of life questionnaire. Qual. Life Res 2007;16:1335-45)
• The self-report version of the Strengths and Difficulties Questionnaire assesses mental well-being (Muris P, Meesters C, Eijkelenboom A, et al. The self‐report version of the Strengths and Difficulties Questionnaire: Its psychometric properties in 8‐to 13‐year‐old non‐clinical children. British Journal of Clinical Psychology 2004;43:437-48)
• The short version of the Social and Community Opportunities Profile (SCOPE) assesses social inclusion indicators (Huxley P, Evans S, Madge S, et al. Development of a social inclusion index to capture subjective and objective life domains (phase II): psychometric development study. Health Technology Assessment 2012;16:1-248)
• Multi-domains of self-perception (Wichstraum L. Harter’s Self-Perception Profile for Adolescents: Reliability, validity, and evaluation of the question format. Journal of personality assessment 1995;65:100-16 and Harter S. Self-perception profile for adolescents: Manual and questionnaires. Denver, CO: University of Denver, Department of Psychology 2012)
• The Child and Youth Resilience Measure (Ungar M, Liebenberg L. Assessing resilience across cultures using mixed methods: Construction of the child and youth resilience measure. Journal of Mixed Methods Research 2011;5:126-49)
• Family functioning and values (Bjelland M, Hausken SE, Sleddens EF, et al. Development of family and dietary habits questionnaires: the assessment of family processes, dietary habits and adolescents’ impulsiveness in Norwegian adolescents and their parents. International Journal of Behavioral Nutrition and Physical Activity 2014;11:130)
• Family activities (Israel AC, Roderick HA. A measure of the stability of family activities: An initial examination. Assessment 2001;8:417-24)
• Family coping strategies (Schumm WR, Bolsen NF. Family measurement techniques: The family coping strategies scale. American Journal of Family Therapy 1985;13:67-71)
• Perceived discrimination (Berry JW, Kyunghwa K, Liebkind K, Sabatier C, Sam DL, Virta E, Phinney J. The questionnaire for International Comparative Study of Ethnocultural Adolescents (The ICSEY project). The questionnaire for International Comparative Study of Ethnocultural Adolescents. 1993)
• Acculturation (Berry JW, Phinney JS, Sam DL, Vedder P. Immigrant youth: Acculturation, identity, and adaptation. Applied psychology. 2006 Jul;55(3):303-32)
• Acculturative stress (Pachter LM, Szalacha LA, Bernstein BA, et al. Perceptions of Racism in Children and Youth (PRaCY): Properties of a self-report instrument for research on children’s health and development. Ethnicity & health 2010;15:33-46)
• Social support addressing emotional and tangible support from family and friends (Oppedal B. Psychosocial profiles as mediators of variation in internalizing problems among young immigrants with origins in countries of war and internal conflicts. European Journal of Developmental Psychology. 2008 Mar 1;5(2):210-34)
• The Host and Heritage Culture Competence Scale for Adolescents assesses culture competence (Oppedal B. Adolescent mental health in multi-cultural context. Department of Psychology, University of Oslo; 2003)
• Peer/friendship relationship and quality (Parker JG, Asher SR. Friendship and friendship quality in middle childhood: Links with peer group acceptance and feelings of loneliness and social dissatisfaction. Developmental Psychology 1993;29:611)
• Social status (Goodman E, Adler NE, Kawachi I, et al. Adolescents’ perceptions of social status: development and evaluation of a new indicator. Pediatrics 2001;108:e31-e)
• Attitudes towards school and school engagement (Glanville JL, Wildhagen T. The measurement of school engagement: Assessing dimensionality and measurement invariance across race and ethnicity. Educational and Psychological Measurement 2007;67:1019-41)
• Social and ethnic identity (Behtoui A. Constructions of self-identification: children of immigrants in Sweden. Identities. 2019 Sep 8:1-20)
• Political trust and engagement (Bennion LD, Adams GR. A revision of the extended version of the objective measure of ego identity status: An identity instrument for use with late adolescents. Journal of Adolescent Research 1986;1:183-97)
• Central capabilities of children (Biggeri M, Libanora R, Mariani S, et al. Children conceptualizing their capabilities: results of a survey conducted during the first children’s world congress on child labour. Journal of Human Development 2006;7:59-83)
• Preferences and plans for the future

Parent instruments (reference in parenthesis):

• Subjective well-being (quality of life measures) (Ware JE, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): i. conceptual framework and item selection. Medical Care 1992;30:473-83)
• Mental well-being (Mollica RF, Wyshak G, de Marneffe D, et al. Indochinese versions of the Hopkins Symptom Checklist-25: a screening instrument for the psychiatric care of refugees. The American journal of psychiatry 1987)
• Parental stress (Berry JO, Jones WH. The parental stress scale: Initial psychometric evidence. Journal of Social and Personal Relationships 1995;12:463-72)
• Daily hassles (Crnic KA, Greenberg MT. Minor parenting stresses with young children. Child development 1990;61:1628-37)
• Perceived discrimination (Flores E, Tschann JM, Dimas JM, et al. Perceived discrimination, perceived stress, and mental and physical health among Mexican-origin adults. Hispanic Journal of Behavioral Sciences 2008;30:401-24)
• Acculturative stress (Jibeen T, Khalid R. Development and preliminary validation of multidimensional acculturative stress scale for Pakistani immigrants in Toronto, Canada. International Journal of Intercultural Relations. 2010 May 1;34(3):233-43)
• Cultural competence (Wilson, J., Ward, C., Fetvadjiev, V. H., & Bethel, A. (2017). Measuring Cultural Competencies: The Development and Validation of a Revised Measure of Sociocultural Adaptation. Journal of Cross-Cultural Psychology, 48(10), 1475-1506)  
• Life events (Brugha, T., Bebbington, P., Tennant, C., & Hurry, J. (1985). The List of Threatening Experiences – A subset of 12 life event categories with considerable long-term contextual threat. Psychological Medicine, 15, 189-194)
• Social support (Sarason, I. G., Levine, H. M., Basham, R. B., & Sarason, B. R. (1983). Assessing Social Support – the Social Support Questionnaire. Journal of Personality and Social Psychology, 44, 127-139.)
• Cultural perceptions and values (Perceived relational mobility using Thomson, R., Yuki, M., Talhelm, T., Schug, J., Kito, M., Ayanian, A. H., . . . Visserman, M. L. (2018). Relational mobility predicts social behaviors in 39 countries and is tied to historical farming and threat. Proceedings of the National Academy of Sciences; Social tightness using Gelfand, M. J., Raver, J. L., Nishii, L., Leslie, L. M., Lun, J., Lim, B. C., . . . Yamaguchi, S. (2011). Differences between tight and loose cultures: A 33-nation study. Science, 332(6033), 1100-1104; and Values using World Value Survey. (2014). World values survey wave 6: 2010-2014. Retrieved from Madrid, Spain: http://www.worldvaluessurvey.org/) 
• Social trust (ESS. (2014). ESS Round 7: European Social Survey Round 7 Data. In E. ERIC (Ed.), 2014)