Static and dynamic accuracy of a magnetic-inertial measurement unit used to provide racket swing kinematics     

Benjamin Kane Williams  Ross H. Sanders  Joong Hyun Ryu  Pitre C. Bourdon  Philip Graham-Smith  Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(2):202-214

Magnetic-inertial measurement units (MIMUs) are becoming more prevalent in sports biomechanics and may be a viable tool to evaluate kinematic parameters. This study examined the accuracy of a MIMU to estimate orientation angles under static conditions and dynamically from a squash racket during a forehand drive shot. A MIMU was mounted onto a goniometer and moved through 0–90°, with static data collected at 10° increments during 10 repetitions of all three axes. Typical error analyses showed the MIMU to be very reliable (TE ≤ 0.03°). MIMU accuracy was determined via intraclass correlation coefficients (ICC) (r > 0.999, p < 0.001). An ordinary least products regression showed no proportional bias and minimal fixed bias for all axes. Dynamic accuracy was assessed by comparing MIMU and optical motion capture data of squash racket swing kinematics. A MIMU was fixed onto a racket and 10 participants each hit 10 forehand shots. Mean orientation angle error at ball impact was <0.50° and ICC showed very high correlations (r ≥ 0.988, p < 0.001) for all orientations. Swing phase root mean squared errors were ≤2.20°. These results indicate that a MIMU could be used to accurately and reliably estimate selected racket swing kinematics.  相似文献   

排名的困境     

菲利普·G·阿特巴赫  张东辉 《学位与研究生教育》2007,(7):11-12

分析了大学排行榜产生的原因,指出了大学排名活动中存在的问题,如评估指标的选取、大学的不同定位等,进而指出世界范围内的排名活动会加大英语国家大学的强势,不利于发展中国家大学的发展,并认为大学排名活动应以准确的评估和科学的指标体系作为基础。  相似文献   

Validation of self-report measures of physical activity: a case study using the New Zealand Physical Activity Questionnaire     

Mackay LM  Schofield GM  Schluter PJ 《Research quarterly for exercise and sport》2007,78(3):189-196

Accurate measurement of physical activity is fundamentally important in epidemiological research of physical activity behavior A widely used telephone-based physical activity questionnaire was compared with other methods of administration and objective measures (pedometers and accelerometers) among 80 adults (43 women). The telephone questionnaire was comparable to both the self-administered form and international telephone-administered equivalent. Although moderate correlation coefficients with objective measures supported the use of the questionnaire, wide prediction intervals generated using Bland Altman methods highlighted large discrepancies between the measures, particularly in the moderate intensity category. These findings illustrate the limitations of correlation coefficients in validation studies and the inaccuracy of self-report questionnaires in measuring physical activity.  相似文献   

Disburdened valves     

Philip Mayer 《Journal of The Franklin Institute》1870,90(6):361-364

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Caple's seven laws of luck     

Philip Seyer 《Performance Improvement》1988,27(9):20-20

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Within‐High‐School Versus Across‐High‐School Scaling of Admissions Assessments: Implications for Validity and Diversity Effects          下载免费PDF全文

Jack W. Kostal  Paul R. Sackett  Nathan R. Kuncel  Philip T. Walmsley  Melissa S. Stemig 《Educational Measurement》2017,36(1):39-46

Previous research has established that SAT scores and high school grade point average (HSGPA) differ in their predictive power and in the size of mean differences across racial/ethnic groups. However, the SAT is scaled nationally across all test takers while HSGPA is scaled locally within a school. In this study, the researchers propose that this difference in how SAT scores and HSGPA are scaled partially explains differences in validity and subgroup differences. Using a large data set consisting of 170,390 students each of whom matriculated at one of 114 separate colleges, the researchers find that awarding SAT scores by ranking SAT within a high school generally results in substantial reduction in the size of subgroup mean differences for this predictor. However, validity for predicting first‐year GPA is also reduced by a small amount. Conversely, placing HSGPA onto a nationally normed metric through the use of multiple regression procedures results in a moderate increase in the size of subgroup mean differences, while also producing a small increase in validity. Taken together, these findings suggest that differences in predictor scaling can partially explain differences in the size of subgroup mean differences between HSGPA and SAT scores and have implications for predictive power.  相似文献   

Forum: Beyond 2000     

Harry Collins  Steven French  R. Millar  J. Osborne  W. F. Vinen  Philip Wright 《Studies in Science Education》2013,49(1):167-173

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DEVELOPMENTAL AND REMEDIAL STUDIES     

Philip Himelstein 《The Educational forum》2013,77(2):261-262

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Preparation in the Art of Teaching English     

Philip D. Ortego 《College Teaching》2013,61(2):117-120

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BOOK REVIEWS     

Liz Brooker  Philip Woods 《教育政策杂志》2013,28(3):357-362

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