The population of this study was Iranian adolescents between 11 and 18 years old who were enrolled in the seventh to twelfth grades. A convenience sample of 822 Adolescents from four large cities in the Iran (Tehran, Zanjan, Hamedan and Ghazvin) participated in the present study. They were relatively proportional distributed by sex: 430 girls (52%) and 392 boys (48%). The mean age was 16.33 years old (SD = 8.80). The highest percentage of the participants (38.6%; n = 317) lived in Tehran province, 20% (n = 165) lived in Zanjan province, 22% (n = 179) lived in Hamedan province 18.7% (n = 154) lived in Ghazvin province and only 7 cases did not report their residence. Concerning their socioeconomic status, the majority (68.1%, n = 560) described itself as belonging to the middle class, 19.9% (n = 164) to middle-low or lower class, 9.2% (n = 76) to high or middle-high class, and 2.6% (n = 22) did not report their class. In the Iranian educational system, the first and second secondary education are included from the seventh to the twelve grade. Most of the participants (58%, n=479) were enrolled in the second secondary, compared to 42% (n=345) who were enrolled in the first secondary education. In terms of educational grade the sample consisted 95 7th graders (11.5%), 115 8th graders (13.9%), 135 9th graders (36.5%), 164 10th graders (36.5%), 195 11th graders (36.5%), and 120 12th graders (36.5%).
The executive process of this research has been approved by the Ethics Committee of Kermanshah University of Medical Sciences under No. IR.KUMS.REC.1400.608 all procedures were carried out an adequate understanding and each participant provided their informed consent prior to the study. Data was collected through non-random and voluntary sampling. Iranian adolescents were asked to complete online questionnaires. Questionnaires were provided for online implementation and administered from November 28th 2020 to February 16th 2021. Before completing the questionnaires, the participants were explained the purposes and significance of research and their informed consent was obtained. For subjects under 16 years of age, the questionnaire link was first provided to their parents and after their consent, the questionnaire link was provided to their children.
The original 14-item Mental Health Continuum–Short Form (MHC-SF) (30) is a self-report questionnaire, measuring three basic subjective well-being domains: emotional (3 items), psychological (6 items) and social (5 items) of well-being. Respondents rated the frequency of every feeling in the past month on a 6-point Likert scale. Respondents thought about their past month and rated the frequency of each feeling on a 6-point Likert-type scale from never (0) to every day (5). The Iranian version of this questionnaire has already been used and validate by Rafiey et al. (34) in the adult population. The original English MHC-SF (30) for adolescent is just like the adult version, with only one helpful change to better fit the adolescent population. Specially, Examples of the community in the item “How often did you feel that you belonged to a community?” which in the adult version was “(like a social group, your neighborhood, or your city)” were given in the adolescent version as “(like a group of friends, at school, or in the neighborhood)”.
The positive affect (PA) dimension of the 10-item PANAS-C (35) was selected to evaluate emotional well-being, as referred to the degree to which people feel is vitality and enthusiastic. The PA dimension was evaluated five adjective by five items: happy, lively, happy, energetic, and proud. The items have a 5-point Likert response format with answers ranging from 1 („very little) to 5 („a lot’). The sum of the item scores gives the total health score. The PA dimension has been shown to measure PA markers well among 6–18-year-olds. Ebesutani et al. (35) showed that PANAS-C is valid and reliable for the age group of 18-18 years. Lotfi (36) reported the psychometric properties of this questionnaire very well in Iran. In the present study, the Cronbach’s alpha of the PANAS-C was 0.76.
Kidscreen-27 (37) is a brief screening measure to evaluate the behavioral and emotional problems of children and adolescents by 27 items measuring five scales, physical well-being, psychological well-being, autonomy and parents, peers and social support, and school environment. Items are scored on a 5-point Likert scale. The higher the total score indicates greater quality of life.Nik-Azin, Naeinian and Shairi (38) reported the psychometric properties of this questionnaire in Iran suitable for the age group of 11 to 19 years. The results of this study supported the five-factor structure of the original version. In the present study, the Cronbach’s alpha of the Kidscreen-27 was 0.73.
The DASS‐21 (39) is a short form of DASS-42, well‐established instrument for measuring depression, anxiety, and stress with good reliability and validity reported in different cultural context (40). DASS-21 is a set of three self-report 7-item scales for assessing negative mental states in anxiety, depression, and stress. All 21 items are scored on a 4-point Likert scale from 0) did not apply to me at all) to 3 (applied to me very much, or most of the time). Asghari (41), examining the psychometric properties of this questionnaire in Iran, reported it as valid and reliable. A high score indicates psychological distress on each scale. In the present study, the Cronbach’s alpha of the DASS‐21 was 0.75.
Data analysis method
After data collection and data screening in the first stage, and after discarding 21 questionnaires with missing or distorted data, the main analyzes were performed with spss-26 and Lisrel-10.2 software.
Face validity: The purpose of face validity is to ensure that respondents understand the items. In this study, face validity was evaluated quantitatively and qualitatively. For qualitative face validity, the questionnaire was provided to 15 participants of the target population to determine the degree of appropriateness, the level of difficulty, and the ambiguity of the items. For quantitative face validity, 30 adolescents determined the importance of the items in relation to the goal of the study. The impact score of each item was measured based on the formula: average × ratio of individuals who have chosen the most important and important option divided by the total number of individuals. The items with an impact score of more than 1.5 were accepted (42).
Content validity: Content validity was evaluated both quantitatively and qualitatively. To evaluate the quantitative content validity, an expert panel of 10 people was formed including 8 child and adolescent psychologists and 2 psychometricians and they were asked to comment on the necessity of each item. Based on this, the value of content validity index (CVI) and Content Validity Ratio (CVR) was calculated. As a criterion, the acceptable value for CVI of each item is 0.7 and more. The expert panel was also asked to rate the items of the questionnaire in terms clarity of the items. To test qualitative content validity, the experts provided their comments on grammar, editing points, use of appropriate words, sentence structure, etc. for each item (43).
Factorial validity: After confirming the face validity and content of the items, the factorial validity was assessed using confirmatory factor analysis. LISREL10.2 was used to evaluate the factor structure. The method of estimating the weighted least squares with data from polychoric matrix and asymptotic covariance matrix was used in data analysis. The least squares method was preferred because the Likert response options were five-choice and the polychoric matrix had to be calculated instead of the Pearson correlation (44).
In this phase, 801 adolescents participated. The model was evaluated using fit indices of chi-square, chi-square to the degree of freedom ratio (X2 / df), standard deviation estimation error (Root Mean Square Error of Approximation), goodness of fit index (GFI), adjusted goodness of fit index (AGFI), Parsimony goodness of fit index (PGFI), Normed Fit Index (NFI) and comparative fit index (CFI) were used. P-value more than .05, X2/df less than three and RMSEA more than 0.08, PGFI more than 0.5, and other indices more than 0.9 were accepted (45).
Measurement Invariance: Multigroup confirmatory factor analysis was performed to evaluate the invariance of the best-fitting model based on gender. Four types of invariance were investigated in this study: configural invariance (Is the configuration of the model the same across groups?), metric/weak invariance (Are factor loadings the same across groups?), scalar/strong invariance (Are the intercepts the same across groups?), and strict invariance (Are the residual variances the same across groups?) across gender (boys vs girls). Configural invariance was confirmed if RSMEA and SRMR were < .08 and CFA was >.95 (46). A relative change of ≤ .010 in CFI, supplemented by a relative change of ≤ .015 in RMSEA or ≤ .030 in SRMR indicated that the null hypothesis of invariance should not be rejected (47).
Construct validity: To evaluate the construct validity, the relationship between the score obtained from MHC-SF-A and several other measures was examined. According to Keyes’ (17) conceptualization, MHC-SF-A is expected to be negatively related to anxiety and depression (convergent validity), Also has a positive relationship with Kidscreen-27 positive affect tests (divergent validity). Pearson correlation coefficient was used to determine the direction and intensity of the relationship between the measures.
Reliability: The reliability of the MHC-SF was determined through internal consistency and composite reliability. value greater than 0.7 was considered acceptable (48).