Educational Attainment as Process: Using Hierarchical Discrete-Time Event History Analysis to Model Rate of Progress

Variables that address student enrollment patterns (e.g., persistence, enrollment inconsistency, completed credit hours, course credit load, course completion rate, procrastination) constitute a longstanding fixture of analytical strategies in educational research, particularly research that focuses on explaining variation in academic outcomes. However, nearly all measures of enrollment patterns are handicapped by untested assumptions about a more fundamental measure, namely students’ rate of progress. In this paper, I first explain how a variety of widely used measures of enrollment patterns are inextricably linked to students’ rate of progress. I then describe a method of modeling mathematically students’ rate of progress that employs hierarchical (multilevel) discrete-time event history analysis of repeated events. I conclude with an empirical example of the application of this method in which I test several hypotheses concerning students’ rate of progress through the remedial math sequence toward the outcome of college-level math competency. In addition to the utility of the method that is proposed here, the issues discussed in this paper have important practical implications for institutional research, particularly with respect to the use of the various measures of enrollment patterns to explain variation in students’ attainment.

复杂网络统计参量对病毒传播速率的影响

复杂网络统计参量是描述复杂网络结构的普适参量,病毒的传播与这些基本参量密切相关,病毒传播速率与复杂网络统计参量间存在确定的联系。文章推论了复杂网络中病毒传播速率与基本网络参量的函数关系。利用这一函数可以在已知的网络结构参数时,得到病毒传播的预测值。     

江海关二五券会运作及作用评析

江海关二五券会作为第一个完全由中国人自己控制的内债基金保管机构,成立于南京国民政府初期,解散于1932年内债整理案后。它一共负责保管了21项内债基金库券,并在其发挥作用期间有着规范的管理运作机制。江海关二五券会有效地维护了国民政府的债信,保护了持券人的利益,是政府和持券人沟通的桥梁。从制度经济学视角看,二五券会发挥了减少信息不对称、降低交易成本、促进债券市场发展的作用。此外,二五券会在运作过程中还起到了约束政府、监督政府的作用。     

Stress reactivity after maximal exercise: The effect of manipulated performance feedback in endurance athletes

This study was designed to assess the effect of performance feedback on stress reactivity after recovery from maximal exercise. Forty competitive athletes were recruited to complete a maximal exercise test. Performance feedback was manipulated after the exercise test to give four groups: (1) high performance, (2) low performance, (3) accurate feedback and (4) no exercise control. Cardiovascular reactivity was assessed during psychological stress. The results indicate that accurate feedback participants experienced lower relative reactivity to stress (lower mean arterial pressure) than their no-exercise counterparts. These results demonstrate that the stressbuffering effect of exercise extends to maximal exercise. In addition, high-performance participants experienced lower relative reactivity than low-performance participants. Thus, low-performance feedback was sufficient to remove the buffering effect of exercise. There were no differences between the high-performance and accurate feedback conditions, or between the low-performance and control conditions.     

Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training

To examine the activity profile and physiological demands of top-class soccer refereeing, we performed computerized time-motion analyses and measured the heart rate and blood lactate concentration of 27 referees during 43 competitive matches in the two top Danish leagues. To relate match performance to physical capacity and training, several physiological tests were performed before and after intermittent exercise training. Total distance covered was 10.07 - 0.13 km (mean - s x ), of which 1.67 - 0.08 km was high-intensity running. High-intensity running and backwards running decreased (P ? 0.05) in the second half. Mean heart rate was 162 - 2 beats· min -1 (85 - 1% of maximal heart rate) and the mean blood lactate concentration was 4.9 - 0.3 (range 1.7-14.0) mmol·l -1 . The amount of high-intensity running during a match was related to the Yo-Yo intermittent recovery test ( r 2 = 0.57; P ? 0.05) and the 12 min run ( r 2 = 0.21; P ? 0.05). After intermittent training ( n = 8), distance covered during high-intensity running was greater (2.06 - 0.13 vs 1.69 - 0.08 km; P ? 0.05) and mean heart rate was lower (159 - 1 vs 164 - 2 beats· min -1 ; P ? 0.05) than before training. The results of the present study demonstrate that: (1) top-class soccer referees have significant aerobic energy expenditure throughout a game and episodes of considerable anaerobic energy turnover; (2) the ability to perform high-intensity running is reduced towards the end of matches; (3) the Yo-Yo intermittent recovery test can be used to evaluate referees' match performance; and (4) intense intermittent exercise training improves referees' performance capacity during a game.     

山东省科技进步贡献率的测算及对策研究

本文基于柯布-道格拉斯函数和索洛余值法,测算了山东省从1990年到2011年间科技进步在经济增长中的作用;通过测算得到的结果,提出了山东省在今后科技发展中的相关对策。     

Bond strength improvement of GFRP rebars with different rib geometries

Based on the Canadian Standards Association (CSA) criteria,105 pullout specimens were tested to investigate the effect of different rib geometries on bond strength of glass fiber reinforced polymer (GFRP) rebars embedded in concrete. Two kinds of conventional reinforcing rebars were also studied for comparison. Each rebar was embedded in a 150 mm concrete cube,with the embedded length being four times the rebar diameter. The experimental parameters were the rebar type,rebar component,rebar diameter,rebar surface texture,rib height,rib spacing and rib width. Theoretical analysis was also carried out to explain the experimental phenomena and results. The experimental and theoretical results indicated that the bond strength of GFRP rebars was about 13%～35% lower than that of steel rebars. The bond strength and bond-slip behavior of the specially machined rebars varied with the rebar type,rebar diameter,rebar surface texture,rib height,rib spacing and rib width. Using the results,design recom-mendations were made concerning optimum rib geometries of GFRP ribbed rebars with superior bond-slip characteristics,which concluded that the optimal rib spacing of ribbed rebars is the same as the rebar diameter,and that the optimal rib height is 6% of the rebar diameter.     

对人民币汇率安排的几点思考

本文从人民币升值的国内外背景、人民币币值稳定的宏观经济意义、人民币升值的利弊及影响人民币汇率变动的因素着手分析，得出在近期内人民币汇率仍应保持稳定。文章进一步提出了考虑到中国未来经济发展的趋势，为保持人民币币值稳定，应适时调整汇率制度，以化解目前的升值压力，提高汇率政策的作用，并提出了相关建议。     

就业率统计偏差的原因探讨

就业率的计算依赖于两个重要指标,一是劳动力资源总量,二是就业人口数。以人口普查资料为基准计算劳动力资源总量比较准确,而由城镇单位劳动统计、工商行政管理对私营企业和个体工商户的行政登记,以及多村就业人员统计三者组成的“三合一”劳动统计得到的就业人口数不准确,存在很多问题,造成就业率统计偏差。     

Uncertain educational returns in a developing economy

This paper estimates the distribution of educational returns by gender for India. While previous studies focus on mean returns, the variance of educational returns has important implications for policy-making and micro-level decision making with respect to education. If the variance of educational returns is large, it can leave large sections of the population with negative returns; if the variance of educational returns is gender specific, it can influence households’ decisions to educate girls versus boys. Our econometric results provide evidence that India's labor markets are characterized by significant uncertainty and that the uncertainty is systematically larger for women.