Towards a unified understanding of relative age effects

Abstract

When athletes are placed into annual age groups to organize and coordinate sport participation, certain (dis)advantages occur as a result of the subtle age differences within these groups. These differences, termed “relative age effects”, have been consistently related to youth and adult sport attainment. However, there has been a lack of consistency in the terminology used in this area of research. In this paper, we consider the operational terms used in relative age research, discuss appropriate applications of terminology, and suggest directions for future research. Importantly, we argue for a unified understanding of what “relative age” means, stressing the need for clarity in directing future advances in the field.     

Examining relative age effects on performance achievement and participation rates in Masters athletes

Abstract

Although the relative age effect has been widely observed in youth sports (Musch & Grondin, 2001 Musch, J. and Grondin, S. 2001. Unequal competition as an impediment to personal development: A review of the relative age effect in sport. Developmental Review, 21: 147–167. [Crossref], [Web of Science ®] , [Google Scholar]), it is unclear whether it generalizes across the lifespan. The purpose of this study was to examine the relative age effect among a population of Masters athletes using archived data. Two successive studies examined the frequency of record-setting achievements (Study 1) and the frequency of participation entries (Study 2) at the US Masters track-and-field and swimming championships as a function of an individual's constituent year within any 5-year age category. Results of Study 1 indicated that the probability of setting a record increased if Masters athletes were in the first year, and decreased if they were in the third, fourth or fifth year, of an age category. Results of Study 2 indicated that the likelihood of participating in the National championships increased if Masters athletes were in the first or second year, and decreased if they were in the fourth or fifth year, of an age category. We highlight and discuss potential advantages afforded to Masters athletes who are relatively younger than their peers in the same 5-year age category.     

论体育体制改革的双重阻力

当今的体育体制改革面临来自既得利益集团和改革阵痛期的双重叠加阻力.来自既得利益集团的阻力称之为相对阻力,因其掌握着体育政策制定的决策权和话语权,对体育体制改革产生强大阻力.来自改革阵痛期的阻力具有人人利益受损的特点,所以称之为绝对阻力,因绝大多数社会公众远离体育政策的决策过程,对体育体制改革产生的阻力有限.针对被永久剥夺利益的特殊利益集团只能以强大的压力迫使其接受改革,除此之外的相对阻力可以采用补偿或者赎买的方式加以解决;绝对阻力是一种无法补偿的阻力,只能选择改革成本与预期收益在合理比的适当时机推进体育体制改革.     

Cross‐Country Skiing

The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross‐country skiing techniques. Eight skilled male cross‐country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross‐country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self‐selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross‐country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross‐country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross‐country skiing techniques.     

The relative age effect among elite youth competitive swimmers

Abstract

The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.     

控制系统稳定性与相对稳定性的数学分析

从数学角度分析了控制系统稳定性及相对稳定性的定义,总结了控制系统稳定性的常用判别方法,并分析了相对稳定性的衡量指标,给出了基于MATLAB控制系统相对稳定性分析的简洁方法。     

HPLC法测定葡萄酒中胭脂红的不确定度评定

根据化学分析中不确定度的评估指南．计算HPLC法测定葡萄酒中胭脂红的不确定度．由供试品的质量引入的不确定度U（M供）：由对照品的质量引入的不确定度U（M对）、由供试品的稀释引入的不确定度U（f供）、由对照品的稀释引入的不确定度U（f对）、由仪器检测引入的不确定度U（f仪器）、由测量结果平均值引入的不确定度U（f）。通过对此不确定度的评定．确定此实验的真实值。从而控制葡萄酒中非法色素的添加．     

相对不起诉制度初探

相对不起诉制度是指检察机关对于存在犯罪嫌疑且符合起诉条件的案件，依其职权而做出的一种不起诉处分。消极裁决权分割、利益居先和宽严相济是该项制度的理论基础。为了使该项制度得以贯彻，必须修改刑事诉讼法，不赋予被不起诉人的申诉权，且对于有被害人的案件，检察机关做出不起诉决定前，应征求被害人意见，赋予被害人知悉权。     

相对不起诉制度质疑

相对不起诉是我国刑事诉讼中的一项重要制度,我国的相对不起诉制度无论在立法规定上还是在司法实践中均存在不尽如人意之处。文章认为应当立法取消人民检察院做出相对不起诉的权力,以避免该制度与无罪推定原则相违背,消除实践中的冲突。在刑事诉讼法做出修改之前,应采取措施保护被害人和被不起诉人的合法权益。     

A method for measuring investment risk based on a relative risk - excess revenue model

This paper identifies the shortcomings of variance and semi-variance methods in investment risk measurement and introduces a new model, namely RR-ER (relative risk and excess revenue) model, which takes account of the revenue over expectation problem. Properties of RR-ER model and the consistency between RR-ER model and traditional risk measure model with regard to continuous random variables are discussed. Case analysis is presented to prove the practicality and efficiency of this new method.