Fitting Unstructured Finite Mixture Models in Longitudinal Design: A Recommendation for Model Selection and Estimation of the Number of Classes

In longitudinal design, investigating interindividual differences of intraindividual changes enables researchers to better understand the potential variety of development and growth. Although latent growth curve mixture models have been widely used, unstructured finite mixture models (uFMMs) are also useful as a preliminary tool and are expected to be more robust in identifying classes under the influence of possible model misspecifications, which are very common in actual practice. In this study, large-scale simulations were performed in which various normal uFMMs and nonnormal uFMMs were fit to evaluate their utility and the performance of each model selection procedure for estimating the number of classes in longitudinal designs. Results show that normal uFMMs assuming invariance of variance–covariance structures among classes perform better on average. Among model selection procedures, the Calinski–Harabasz statistic, which has a nonparametric nature, performed better on average than information criteria, including the Bayesian information criterion.     

山东省体育用品制造业市场结构的实证研究

基于对山东省17地市体育用品制造业,特别是销售收入前8位企业的实证研究,阐述山东省体育用品制造业市场集中度、产品差异化、市场进入、退出壁垒的结构现状,揭示现有市场结构与政府政策、企业经济规模、员工文化素质、产品研发的内在因果联系。旨在进一步优化山东省体育用品制造业市场结构。     

重庆市制造业的绿色经济增长核算:2001—2010

基于生产前沿理论的绿色经济增长核算模型,不仅将技术无效率和环境代价纳入了分析框架,而且还与"物质平衡思路"一致;该模型将绿色经济增长的源泉分解为环境约束下的技术进步、技术效率变化和资本深化3大部分。对重庆市27个制造行业的经验分析结论表明:经济增长中普遍存在着技术无效率现象,但50%以上行业的技术效率都得到了改善或维持不变;资本深化是经济增长的主要源泉,而技术进步主导的全要素生产率变动在其中的贡献相对较小;技术进步是引致全要素生产率增长的主要原因。为充分发挥重庆市制造业可持续发展潜力,后续发展中必须转变经济发展方式,在环境约束下走技术进步和技术效率改善的绿色全要素生产率增长之路。     

Key somatic variables in young backstroke swimmers

The purpose of this study was to estimate the optimal body size, limb-segment length, girth or breadth ratios for 100-m backstroke mean speed performance in young swimmers. Sixty-three young swimmers (boys [n = 30; age: 13.98 ± 0.58 years]; girls [n = 33; age: 13.02 ± 1.20 years]) participated in this study. To identify the optimal body size and body composition components associated with 100-m backstroke speed performance, we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 100-m backstroke mean speed performance and the different somatic measurements estimated that biological age, sitting height, leg length for the lower-limbs, and two girths (forearm and arm relaxed girth) are the key predictors. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. In fact, it is only by adopting multiplicative allometric models that the abovementioned ratios could have been derived. These findings highlighted the importance of considering somatic characteristics of young backstroke swimmers and can help swimming coaches to classify their swimmers and enable them to suggest what might be the swimmers’ most appropriate stroke (talent identification).     

我国体育用品制造业国际转移的趋势及动力机制——基于全球生产网络视角

我国体育用品制造业国际转移呈现出网络化、多元化、集群化、主动化的新趋势,其动力来源有三点,一是寻求我国体育用品制造业价值链的重构,二是试图跨越后发国家可能面临的价值链固化的"网络陷阱",三是追逐包括竞争优势和网络权力等隐形收益在内的综合利益最大化。但是,这种自觉行动和主动作为可能受到价值链上端发达国家的阻击。因此,我国体育用品制造业要利用研发设计和品牌营销价值链的发育突破门限效应,积极开展跨境并购和逆向投资活动弥补比较劣势,并逐步回归到研发本土化,利用国内中小体育用品企业构建由自己主导的价值链,以全球布局应对潜在的贸易风险。     

经济新常态下我国体育用品制造企业主要财务指标比较及对策研究

采用文献资料、比较分析、数理统计等研究方法,围绕企业盈利能力、成长能力、运营能力和偿债能力4个方面,对2012~2015年我国不同登记注册类型的体育用品制造企业的主要财务指标进行比较分析。结果显示：（1）体育用品制造企业的整体盈利水平实现正向增长,盈利能力强弱顺序为集体企业、私营企业、股份制企业、外商和港澳台投资企业、股份合作制企业及国有企业;（2）体育用品制造企业增长速度较快,成长能力强弱顺序为国有企业、集体企业、私营企业、股份制企业、外商和港澳台投资企业、股份合作制企业;（3）运营能力强弱顺序为集体企业、股份合作制企业、私营企业、国有企业、外商和港澳台投资企业、股份制企业;（4）企业偿债能力强弱顺序为集体企业、股份合作制企业、国有企业、外商和港澳台投资企业、股份制企业和私营企业;（5）总体而言,近4年来集体所有制体育用品制造企业的各方面能力均较强,但其余5类企业在各方面能力上的强弱差异性过大,两极分化问题非常突出。据此,以新常态下中国经济发展的基本特征为切入点,从企业组织形式转型、创新创业、品牌建设、政策扶持、人才培养、融资约束、贸易环境等8个方面,提出了我国体育用品制造企业发展的对策和建议。     

‘The life of crime does not pay; stop and think!’: the process of co-constructing a prototype pedagogical model of sport for working with youth from socially vulnerable backgrounds

Purpose: This study discusses the process of co-constructing a prototype pedagogical model for working with youth from socially vulnerable backgrounds.

Participants and settings: This six-month activist research project was conducted in a soccer program in a socially vulnerable area of Brazil in 2013. The study included 17 youths, 4 coaches, a pedagogic coordinator and a social worker. An expert in student-centered pedagogy and inquiry-based activism assisted as a debriefer helping in the progressive data analysis and the planning of the work sessions.

Data collection/analysis: Multiple sources of data were collected, including 38 field journal/observation and audio records of: 18 youth work sessions, 16 coaches’ work sessions, 3 combined coaches and youth work sessions, and 37 meetings between the researcher and the expert.

Findings: The process of co-construction of this prototype pedagogical model was divided into three phases. The first phase involved the youth and coaches identifying barriers to sport opportunities in their community. In the second phase, the youth, coaches and researchers imagined alternative possibilities to the barriers identified. In the final phase, we worked collaboratively to create realistic opportunities for the youth to begin to negotiate some of the barriers they identified. In this phase, the coaches and youth designed an action plan to implement (involving a Leadership Program) aimed at addressing the youths’ needs in the sport program. Five critical elements of a prototype pedagogical model were co-created through the first two processes and four learning aspirations emerged in the last phase of the project.

Implications: We suggest an activist approach of co-creating a pedagogical model of sport for working with youth from socially vulnerable backgrounds is beneficial. That is, creating opportunities for youth to learn to name, critique and negotiate barriers to their engagement in sport in order to create empowering possibilities.     

上海市体育用品制造业技术创新影响因素的实证研究

主要采取文献资料法、问卷调查法、数理统计法等研究方法,以上海市体育用品制造业为实证研究对象,梳理了历年来上海市体育用品制造业技术创新的现状,评估上海市体育用品制造业技术创新的深度和广度,并基于国内外已有相关研究文献,以已有的技术创新量表,结合本国国情和上海市体育用品制造业的具体特征,设计出相关问卷,采用相对重要性指标来识别并测量上海市体育用品制造业技术创新的障碍因素和政策环境。     

中国体育用品制造业月度利润额的季节调整实证研究

首先对中国体育用品制造业月度利润额季节调整的原因、季节调整方法的发展过程及应用状况进行了说明,引用国际上最新流行的X-12-ARIMA和TRAMO／SEATS季节调整方法对国内体育用品制造业月度利润额进行季节调整与分析。结果表明,1999-2007年我国体育用品制造业月度利润额存在着有规律的季节性变化,体育用品制造业月度利润额的时间序列是稳定向上的,且该时间序列的季节性波幅显示出与趋势成比例的特征。体育用品制造业月度利润额在0．1％显著性水平下存在稳定的季节性,但在5％显著性水平下不存在年度间变动的季节性。交易日对体育用品制造业月度利润额不构成显著影响,而节假日因素（即春节）却是影响体育用品制造业月度利润额的重要原因。体育用品制造业月度利润额的最终季节调整序列的最终趋势成分占据着重要地位,而X-12-ARIMA与TRMAO／SEATS两种程序调整所得的最终季节调整序列的显著性差异来自于最终季节成分和最终不规则成分。最后提出我国体育经济时间序列季节调整的一些启示。