Data Sources
The data for this study were obtained from the Chinese Family Panel Studies (CFPS) by implementing the China Social Science Survey Center, Peking University. CFPS conducted initial investigations in Beijing, Shanghai, and Guangdong in 2008 and 2009, and samples were collected from all over China in 2010. CFPS is a national, large-scale, and multidisciplinary social follow-up survey project that includes four main questionnaire types: community questionnaire, family questionnaire, adult questionnaire, and children questionnaire. CFPS had collected data over four rounds. The data analyzed in this study was from a single-round collection in 2014 by children questionnaire. The study protocol and sampling method details can be found elsewhere [29,30].
Adolescents in this study were students aged 10 to 15 years old in the east, north, south, central, northeast, northwest, and southwest regions of China, including 25 provinces, cities and autonomous regions. The representativeness of the sample is very good. A total of 892 adolescents from 871 families were included in the study with complete and significant study questionnaires.
Participants
A total of 892 adolescents from east (15.1%), north (11.3%), south (14.0%), central (19.7%), northeast (10.2%), northwest (16.0%) and southwest (13.6%) China, included 485 (54.4%) boys and 407 (45.6%) girls were included in the current study. The sample was composed of 365 (40.9%) adolescents living in urban areas and 527 (59.1%) adolescents from rural areas. The average age of total boys and girls adolescents was 10.72 (SD=0.89), 10.71 (SD=0.83), and 10.72 (SD=0.96) years, respectively.
Measures Questionnaire design
This research conducted a preliminary survey of 783 adolescents in Beijing, Shanghai, and Guangdong provinces in 2008 and 2009, to improve the operability of the questionnaire survey. Those 783 adolescents were excluded from the formal study because the final questionnaire had been modified according to their feedback. The study is based on the CFPS self-administered questionnaire for adolescents aged 10 to 15 years that covered basic information on age, gender, living condition, educational level, type of residence, self-evaluation, parental bonding instrument, personality traits, and psychological status.
Self-evaluation
Adolescents’ self-evaluation consists of three scales: the Rosenberg Self-Esteem Scale [31], the Nowicki-Strickland Locus of Control Scale for children (NLCS-C) [32], and the Self-Discipline Scale [33]. The Rosenberg Self-Esteem Scale consisted of 10 questions such as “On the whole, I am satisfied with myself,” which was a 4 -point Likert scale (1) “totally disagree” (2) “disagree” (3) “agree” and (4) “totally agree”, with some questions were reverse scored. A higher final sum score for all the ten items indicated higher self-esteem. The NLCS-C scale consisted of 40 yes/no answered questions with a low score indicating internal locus of control and a high score indicating external locus of control. Such as “Do you believe that most problems will solve themselves if you just don’t fool with them?” The Self-Discipline Scale is based on a 5 -point Likert scale (1) “Disagree strongly” (2) “Disagree a little” (3) “Neither agree nor disagree” (4) “Agree a little” and (5) “Agree Strongly”. Of the 12 questions such as “I am good at resisting temptation”, a higher score indicates optimism and higher perceived self-efficacy. However, after the existing and mature scales abroad were introduced to China, researchers also faced the problems of measuring validity and reliability. Because Chinese people tend to be conservative in their responses to the scale, they tend to choose neutral answers rather than the most suitable ones, which leads to inaccurate measurement results. In dealing with this problem, the researchers of CFPS have added or deleted items and modified their scoring to include (1) “totally disagree” (2) “disagree” (3) "neither agree nor disagree” (4) “agree” and (5) “totally agree” to reduce the probability that respondents improperly choose the middle option [34]. The Cronbach's alphas for the respective three scales were 0.88, 0.82, and 0.70.
Parental Bonding Instrument, Personality Traits and Psychological Status
In order to make the scales conform to Chinese people's answering habits and thinking mode and reduce the inaccurate measurement results, the researchers of CFPS have modified these scoring scales a little and re-measured the validity and reliability of the scales [34]. The Parental Bonding Instrument introduced by Parker et al. was used with a 25-items measure of differences in parental bonding. Responses were scored on a 5-point Likert scale ranging from (1) “never” (2) “rarely” (3) “sometimes” (4) “often” and (5) “always”; Cronbach's alpha for the scale was 0.80 [35]. The Personality Scale that was used to assess the personality traits [34] was derived from a sub-scale of the Big Five Questionnaire-Children produced by Barbaranelli et al. [36], with a 12- self-reported items rated from (1) “totally disagree” to (5) “totally agree” and its Cronbach's alpha was 0.77. Kessler measured the psychological status using the Kessler 6 Psychological Distress Scale (K6) [37]. The scale consisted of 6 items scored on a 5- point Likert scale ranging from (1) “always” (2) “often” (3) “sometimes” (4) “rarely” and (5) “never”. Some of the items were reversely scored so that the high total score indicates positive psychological status. The Cronbach's alpha for this scale was 0.649.
Procedure
In brief, the CFPS sample was a multi-stage probability sample extracted by the implicit stratification method. The samples of the subsampling frame were extracted in three stages. The first-stage sampling (primary sampling units, PSUs) were counties (or county-level cities/districts) listed in descending order by a socioeconomic indicator. The second-stage sampling (Secondary sampling units, SSUs) were resident committees and administrative villages from counties (or county-level cities/districts). The third and final stage of sampling (Tertiary sampling units, TSUs) were households from resident committees and administrative villages. In the first two stages of the sampling process, official administrative entities were used. The administrative structure in China has two important features: first, it is strictly hierarchical; and second, at least in theory, it covers the entire population of China exhaustively, without exception. Moreover, to minimize sampling frame errors, it was the random starting point of the circular isometric sampling method that was used to extract sample households in the third stage. The study was designed to include interviews and consider all members over the age of 9 years in a sampled household as core members of the CFPS.
Statistical analysis
SPSS-25.0 and AMOS-24.0 were used for data analyses. The participants’ characteristics were presented as numbers and frequencies. In order to examine the theoretical model which contained the targeted factors, a type of multivariate analysis method, structural equation modeling (SEM), was applied. Initially, a model containing the final scores of the parental bonding instrument, personality traits scale, and psychological status scale with the adolescents’ self-evaluation domains was designed. Then the estimated value and significance level of each parameter were obtained. In addition, in order to explore the heterogeneity caused by demographic characteristics, and tests for heterogeneity for age (<11 and ≥11 years), sex (boy and girl), and living environment (urban and rural) by multigroup analyses of the structural equation modeling considering subgroup sample size³200 [38].
After that, the bivariate correlation analysis (BCA) was used to observe the correlation among the included factors. After the analysis results were confirmed, the proposed hypothesis model was verified and fitted with the structural equation modeling (SEM) analysis of AMOS. The proposed model was confirmed by examining the goodness of fit statistics, which indicted a ratio of the chi-square (χ2) to the degree of freedom (df), a goodness of fit index (GFI), adjusted goodness of fit index (AGFI), comparative fit index (CFI), and root mean square error of approximation (RMSEA). The definition of satisfactory goodness of fit was χ2/df < 2.0, GFI > 0.95, AGFI > 0.90, CFI > 0.97, and RMSEA < 0.05, while the standard of acceptable goodness of fit was χ2/df < 3.0, GFI > 0.90, AGFI > 0.85, CFI > 0.95, and RMSEA < 0.08 [39]. The chi-square difference test was used to check the nested models and if the complex model fitted a higher degree of the data when compared to the simpler model [40]. By comparing the Akaike information criterion (AIC) value of the models, a nested model is proved to be a significant well-fitting model if it was associated with at least 50 units reduction in the measurement [41,42,43].