Harmonic coauthor credit: A parsimonious quantification of the byline hierarchy

In this paper the accuracy of five current approaches to quantifying the byline hierarchy of a scientific paper is assessed by measuring the ability of each to explain the variation in a composite empirical dataset. Harmonic credit explained 97% of the variation by including information about the number of coauthors and their position in the byline. In contrast, fractional credit, which ignored the byline hierarchy by allocating equal credit to all coauthors, explained less than 40% of the variation in the empirical dataset. The nearly 60% discrepancy in explanatory power between fractional and harmonic credit was accounted for by equalizing bias associated with the omission of relevant information about differential coauthor contribution. Including an additional parameter to describe a continuum of intermediate formulas between fractional and harmonic provided a negligible or negative gain in predictive accuracy. By comparison, two parametric models from the bibliometric literature both had an explanatory capacity of approximately 80%. In conclusion, the results indicate that the harmonic formula provides a parsimonious solution to the problem of quantifying the byline hierarchy. Harmonic credit allocation also accommodates specific indications of departures from the basic byline hierarchy, such as footnoted information stating that some or all coauthors have contributed equally or indicating the presence of a senior author.     

Universality of scholarly impact metrics

Given the growing use of impact metrics in the evaluation of scholars, journals, academic institutions, and even countries, there is a critical need for means to compare scientific impact across disciplinary boundaries. Unfortunately, citation-based metrics are strongly biased by diverse field sizes and publication and citation practices. As a result, we have witnessed an explosion in the number of newly proposed metrics that claim to be “universal.” However, there is currently no way to objectively assess whether a normalized metric can actually compensate for disciplinary bias. We introduce a new method to assess the universality of any scholarly impact metric, and apply it to evaluate a number of established metrics. We also define a very simple new metric h_s, which proves to be universal, thus allowing to compare the impact of scholars across scientific disciplines. These results move us closer to a formal methodology in the measure of scholarly impact.     

具免疫时滞的HIV感染系统的稳定性及Hopf分支分析

考虑了具免疫时滞的HIV病毒模型,分析了未感染平衡点的全局渐近稳定性,给出了感染无免疫平衡点和感染免疫平衡点局部渐近稳定的充分条件,并讨论了感染免疫平衡点附近存在Hopf分支的充分条件.最后,通过数值模拟验证了所得结论.     

Relative age effect in elite sports: Methodological bias or real discrimination?

Abstract

Sport science researchers refer to a relative age effect when they observe a biased distribution of elite athletes' birth dates, with an over-representation of those born at the beginning of the competitive year and an under-representation of those born at the end. Based on the complete sample of French male licensed soccer players (n=1,831,524), we suggest that there could be an important bias in the statistical test of this effect. This bias could in turn lead to the false conclusion of systemic discrimination in the recruitment of professional players. Our findings question the accuracy of previous research on the existence of this effect in elite soccer.     

Reliability and validity of judging in women's artistic gymnastics at University Games 2009

Abstract

The aim of our research was to analyse the reliability and validity of judging on all women's apparatuses and all sessions (qualification, all round finals and apparatus finals) at the World University Games-Universiade 2009 in Belgrade. For validity assessment, mean absolute and rank deviations of judges’ execution scores were calculated. For consistency and reliability assessment, Cronbach's alpha coefficient, intra-class correlations, Armor's theta and Kendall's W coefficient were calculated. Vault and floor exercise finals were the sessions with the highest scores and the lowest score dispersion. The overall highest individual judge average absolute deviation was 0.34 point and the largest mean rank deviation was 0.88 with most values well below this. A correlation matrix for between-judge correlations identified three judges (out of 20) in the apparatus finals sessions with remarkably inferior correlations with others. Except for vault and floor finals, the results in terms of consistency (Cronbach's alpha mostly above 0.95) and reliability (Armor's theta mostly above 0.94, intra-class correlation for single and average measures above 0.87 and 0.94, respectively) were satisfactory. In conclusion, overall high values of reliability and consistency indices were found. Sessions where the variability between competitors is low (such as vault and floor finals in this competition) should be inspected with special care in future judging analyses.     

Where are all the female participants in Sports and Exercise Medicine research?

Abstract

The aim of this study is to estimate the ratio of male and female participants in Sports and Exercise Medicine research. Original research articles published in three major Sports and Exercise Medicine journals (Medicine and Science in Sports and Exercise, British Journal of Sports Medicine and American Journal of Sports Medicine) over a three-year period were examined. Each article was screened to determine the following: total number of participants, the number of female participants and the number of male participants. The percentage of females and males per article in each of the journals was also calculated. Cross tabulations and Chi-square analysis were used to compare the gender representation of participants within each of the journals. Data were extracted from 1382 articles involving a total of 6,076,580 participants. A total of 2,366,968 (39%) participants were female and 3,709,612 (61%) were male. The average percentage of female participants per article across the journals ranged from 35% to 37%. Females were significantly under-represented across all of the journals (χ² = 23,566, df = 2, p < 0.00001). In conclusion, Sports and Exercise Medicine practitioners should be cognisant of sexual dimorphism and gender disparity in the current literature.     

我国优秀女子长跑运动员核心稳定性的研究

以我国12名优秀女子长跑运动员为研究对象,应用BTE多功能肌力测试系统,对我国优秀长跑运动员核心稳定性进行综合评价。在对测试结果分析的基础上,制定有针对性的训练手段与方法,为我国优秀女子长跑运动员核心稳定性的提高提供帮助。     

Open feedback in gymnastic judging causes conformity bias based on informational influencing

Abstract

The aims of this study were twofold: (1) to determine whether open feedback (i.e. the ability to hear or see the scores of colleague judges after each performance) would lead judges in gymnastics to conform with their colleagues, and (2) to identify the underlying process on which this conformity is based. Twenty-three certified Flemish judges in women's gymnastics were randomly divided into panels of a maximum of five judges. These panels had to rate the same 30 videotaped individual vaults: 15 in phase 1 and 15 in phase 2. Two independent variables were orthogonally manipulated: feedback (or no feedback) during phase 1 and feedback (or no feedback) during phase 2. The results of phase 1 revealed that the variation between the judges' scores was less within panels that had received feedback than within panels that had not received feedback. We therefore conclude that the availability of feedback elicits conformity among gymnastic judges. The results of phase 2 indicated that this conformity continued even when feedback was no longer provided, suggesting that the observed conformity was based on informational influencing (i.e. because of uncertainty about the correct responses) and not on normative influencing (i.e. out of fear of standing out in the group).     

Dual-task effect on postural control in high-level competitive dancers

Abstract

We investigated balance in 33 competitive dancers (17 females, 16 males) and 22 controls (17 females, 5 males) (age 16–27 years) on a force plate in two conditions: single task (quiet stance) and dual task (with a concurrent mental task). Balance was evaluated using centre-of-pressure shift (sway) variability, mean speed, frequency, and sample entropy. The effect of the dual task in the medio-lateral plane was comparable in both groups, decreasing sway variability (P < 0.05) and increasing mean speed (P < 0.001), frequency, and sample entropy (P < 0.001), showing that the participants effectively increased the level of automaticity. In the antero-posterior plane, the dual task also increased sway frequency and sample entropy (P < 0.01) in dancers without affecting their standing performance. In contrast, postural control in non-dancers was vulnerable to reduced cognitive investment, which adversely interfered with baseline performance. There were very high correlations between sway sample entropy and frequency in each group, plane, and task (r = 0.92–0.98, P < 0.001), indicating that both parameters may measure the same characteristic of postural control and that higher sway frequency may play an important role in protecting stability in dual tasking. The postural control of dancers and non-dancers appears to be similar, although dancing seems to facilitate the increased level of automatic control in the antero-posterior plane.