Association of Reallocating Time in Different Intensities of Physical Activity with Weight Status Changes among Normal-Weight Chinese Children: A National Prospective Study

Background: Time spent in different intensity-specific physical activities is codependent, but the substitution effect of different activities on weight status changes in children remains unclear. This study aims to investigate the prospective association between reallocating time in different intensities of physical activity and weight status changes among Chinese children. Methods: A national sample of 15,100 normal-weight children aged 7–18 years (46.7% boys) were recruited in September 2013 and followed up for nine months. Vigorous-intensity physical activity (VPA), moderate-intensity physical activity (MPA), walking, and sedentary time were obtained by International Physical Activity Questionnaire Short Form (IPAQ-SF). Height and weight were objectively measured, by which body mass index (BMI) and BMI z-score were calculated. Weight status was classified by the Chinese criteria for 7- to 18-year-old children. Isotemporal substitution analyses (including single-factor model, partition model, and isotemporal substitution model) were applied to examine the association of time allocation with weight status changes. Results: Each 30 min/day of increase in VPA was favorably associated with a 13.2% reduced risk of incident overweight/obesity in a single-factor model and a 15.6% reduced risk in a partition model. Negative associations were found between VPA, MPA, walking and the risk of being underweight in the single-factor model, but not in the partition model. In substitution models, replacing 30 min/day sedentary time with an equal amount of VPA was favorably associated with a 16.1% reduction of the risk of being overweight/obese. Conclusion: These findings highlight the need for promoting vigorous-intensity physical activity in children.

The Factor Structure and Gender Invariance of ADHD Symptoms in College Students

Previous studies examining the factor structure of attention-deficit/hyperactivity disorder (ADHD) symptoms in adults using self-report measures have shown mixed results, supporting two-, three-, and bifactor solutions. The current study further investigated the structure of ADHD symptoms in adults using the Current Symptoms Scale and rigorous model evaluation in a sample of 892 college students. Confirmatory factor analysis was used to analyze and compare five-factor structures; a single-factor model, a two-factor model, a three-factor model, and two bifactor models. A single-factor model with correlated residuals best fit the data. Factor correlations with nearly all related constructs (i.e., symptoms of oppositional defiant disorder, depression, impairment, previous ADHD diagnosis, grades, and substance use) were significant in the expected directions and the model was invariant across gender. These findings contribute to a growing body of work suggesting a unidimensional factor may best represent ADHD symptoms in adults. Implications are discussed.

Three recommendations based on a comparison of the reliability and validity of the predominant models used in research on the empirical structure of psychopathology

The present study compared the primary models used in research on the structure of psychopathology (i.e., correlated factor, higher-order, and bifactor models) in terms of structural validity (model fit and factor reliability), longitudinal measurement invariance, concurrent and prospective predictive validity in relation to important outcomes, and longitudinal consistency in individuals’ factor score profiles. Two simpler operationalizations of a general factor of psychopathology were also examined—a single-factor model and a count of diagnoses. Models were estimated based on structured clinical interview diagnoses in two longitudinal waves of nationally representative data from the United States (n = 43,093 and n = 34,653). Models that included narrower factors (fear, distress, and externalizing) were needed to capture the observed multidimensionality of the data. In the correlated factor and higher-order models these narrower factors were reliable, largely invariant over time, had consistent associations with indicators of adaptive functioning, and had moderate stability within individuals over time. By contrast, the fear and distress specific factors in the bifactor model did not show good reliability or validity throughout the analyses. Notably, the general factor of psychopathology (p-factor) performed similarly well across tests of reliability and validity regardless of whether the higher-order or bifactor model was used; the simplest (single-factor) model was also comparable across most tests, with the exception of model fit. Given the limitations of categorical diagnoses, it will be important to repeat these analyses using dimensional measures. We conclude that when aiming to understand the structure and correlates of psychopathology it is important to: 1) look beyond model fit indices to choose between different models; 2) examine the reliability of latent variables directly; and 3) be cautious when isolating and interpreting the unique effects of specific psychopathology factors, regardless of which model is used.

Cross-Cultural Evaluation of Antonovsky’s Orientation to Life Questionnaire: Comparison Between Australian, Finnish, and Turkish Young Adults

Antonovsky’s concept “sense of coherence” (SOC) and the related measurement instrument “The Orientation to Life Questionnaire” (OLQ) has been widely applied in studies on health and well-being. The purpose of the present study is to investigate the cultural differences in factor structures and psychometric properties as well as mean scores of the 13-item form of Antonovsky’s OLQ among Australian (n = 201), Finnish (n = 203), and Turkish (n = 152) students. Three models of factor structure were studied by using confirmatory factor analysis: single-factor model, first-order correlated-three-factor model, and the second-order three-factor model. Results obtained in all three countries suggest that the first- and second-order three-factor models fitted the data better that the single-factor model. Hence, the OLQ scoring based on comprehensibility, manageability, and meaningfulness scales was supported. Scale reliabilities and inter-correlations were in line with those reported in earlier studies. Two-way analyses of variance (gender × nationality) with age as a covariate showed no cultural differences in SOC scale scores. Women got higher scores on the meaningfulness scale than men, and age was positively related to all SOC scale scores indicating that SOC increases in early adulthood. The results support the three-factor model of OLQ which thus should be used in Australia, Finland, and Turkey instead of a single-factor model. Need for cross-cultural studies taking into account cultural correlates of SOC and its relation to health and well-being indicators as well as studies on gender differences in the OLQ are emphasized.

Review and Validity of Capital Asset Pricing Model: Evidence from Pakistan Stock Exchange

Since the inception of prospects theory of Markowitz (1952) which leads to the development of CAPM has been studied and applied in many ways. Some researchers conclude that CAPM is valid and could be used for valuation of securities and cost of equity. However, critiques arise that CAPM is a single risk factor and remark that a single factor model cannot be generalized in the overall capital markets because the capital market absorbs many other risk factors. The CAPM has been applied to the Pakistan’s Stock Exchange to check the validity of CAPM for a sample of 306 individual firms and 18 industrial portfolios. Two pass regression has been applied to check the applicability of CAPM in Pakistan’s stock exchange. The results show that CAPM, single factor model is not valid for the technical analysis in Pakistan's capital market. The investors need to use other type of factor models which include other economic and non economic kind of variables for valuation of securities.