1,873 research outputs found
Bayesian correction for covariate measurement error: a frequentist evaluation and comparison with regression calibration
Bayesian approaches for handling covariate measurement error are well
established, and yet arguably are still relatively little used by researchers.
For some this is likely due to unfamiliarity or disagreement with the Bayesian
inferential paradigm. For others a contributory factor is the inability of
standard statistical packages to perform such Bayesian analyses. In this paper
we first give an overview of the Bayesian approach to handling covariate
measurement error, and contrast it with regression calibration (RC), arguably
the most commonly adopted approach. We then argue why the Bayesian approach has
a number of statistical advantages compared to RC, and demonstrate that
implementing the Bayesian approach is usually quite feasible for the analyst.
Next we describe the closely related maximum likelihood and multiple imputation
approaches, and explain why we believe the Bayesian approach to generally be
preferable. We then empirically compare the frequentist properties of RC and
the Bayesian approach through simulation studies. The flexibility of the
Bayesian approach to handle both measurement error and missing data is then
illustrated through an analysis of data from the Third National Health and
Nutrition Examination Survey
Perceptions of sport science students on the potential applications and limitations of blended learning in their education: A qualitative study
This study sought to gain insight into blended learning-naive sports science studentsâ understanding and perceptions of the potential benefits and limitations of blended (hybrid) learning, which has been defined as the thoughtful integration of face-to-face and online instructional approaches. Five focus groups, each comprising 3â4 students from either the undergraduate or postgraduate sports science programmes were conducted. The focus groups were facilitated by a researcher who was not involved in sports science. Audio recordings of the focus groups were transcribed verbatim. NVivo software was used to code the transcripts to identify the themes and subthemes. Students generally had little initial understanding of blended learning. When provided with a definition, they believed that blended learning could improve educational outcomes and assist those who were legitimately unable to attend a session. Their reservations about blended learning mainly related to some students not being sufficiently autonomous to undertake independent study, timetabling considerations and access to reliable Internet services. For blended learning to be effective, students felt the online material had to be interactive, engaging and complement the face-to-face sessions. Better understanding the perceptions of the students in the current study may assist educators who are considering implementing blended learning in their teaching. © 2017 Informa UK Limited, trading as Taylor & Francis Grou
Tapering practices of strongman athletes: Test-retest reliability study
BACKGROUND: Little is currently known about the tapering practices of strongman athletes. We have developed an Internet-based comprehensive self-report questionnaire examining the training and tapering practices of strongman athletes. OBJECTIVE: The objective of this study was to document the test-retest reliability of questions associated with the Internet-based comprehensive self-report questionnaire on the tapering practices of strongman athletes. The information will provide insight on the reliability and usefulness of the online questionnaire for use with strongman athletes. METHODS: Invitations to complete an Internet questionnaire were sent via Facebook Messenger to identified strongman athletes. The survey consisted of four main areas of inquiry, including demographics and background information, training practices, tapering, and tapering practices. Of the 454 athletes that completed the survey over the 8-week period, 130 athletes responded on Facebook Messenger indicating that they intended to complete, or had completed, the survey. These participants were asked if they could complete the online questionnaire a second time for a test-retest reliability analysis. Sixty-four athletes (mean age 33.3 years, standard deviation [SD] 7.7; mean height 178.2 cm, SD 11.0; mean body mass 103.7 kg, SD 24.8) accepted this invitation and completed the survey for the second time after a minimum 7-day period from the date of their first completion. Agreement between athlete responses was measured using intraclass correlation coefficients (ICCs) and kappa statistics. Confidence intervals (at 95%) were reported for all measures and significance was set at P<.05. RESULTS: Test-retest reliability for demographic and training practices items were significant (P<.001) and showed excellent (ICC range=.84 to .98) and fair to almost perfect agreement (Îș range=.37-.85). Moderate to excellent agreements (ICC range=.56-.84; P<.01) were observed for all tapering practice measures except for the number of days athletes started their usual taper before a strongman competition (ICC=.30). When the number of days were categorized with additional analyses, moderate reliability was observed (Îș=.43; <.001). Fair to substantial agreement was observed for the majority of tapering practices measures (Îșrange=.38-.73; P<.001) except for how training frequency (Îș=.26) and the percentage and type of resistance training performed, which changed in the taper (Îș=.20). Good to excellent agreement (ICC=.62-.93; P<.05) was observed for items relating to strongman events and traditional exercises performed during the taper. Only the time at which the Farmer's Walk was last performed before competition showed poor reliability (ICC=.27). CONCLUSIONS: We have developed a low cost, self-reported, online retrospective questionnaire, which provided stable and reliable answers for most of the demographic, training, and tapering practice questions. The results of this study support the inferences drawn from the Tapering Practices of Strongman Athletes Stud
A biomechanical analysis of the heavy sprint-style sled pull and comparison with the back squat
This study compared the biomechanical characteristics of the heavy sprint-style sled pull and squat. Six experienced male strongman athletes performed sled pulls and squats at 70% of their 1RM squat. Significant kinematic and kinetic differences were observed between the sled pull start and squat at the start of the concentric phase and at maximum knee extension. The first stride of the heavy sled pull demonstrated significantly (
Examination Of An Independent Schoolâs Site-Based Summer Program
This study examined the summer program offered by a pre-kindergarten through grade twelve independent school. Three levels of theory, individual, group, and organizational, were utilized to analyze the experiences of students and instructors. The variety of opportunities and instructional design elements, the intentional alignment to the traditional school year, collegial discussions connecting summer learning and the school year, and evidence of the schoolâs mission were examined.
Findings revealed a wide-range of educational experiences and the benefits of continuous learning that are evident the following school year. Class designs incorporated instructional elements supported by individual learning theories. Academic standards and expectations aligned to the traditional school year; summer classes have developed in tandem with curriculum refinements. Instructors valued the opportunities for more frequent collegial discussions and professional development. The schoolâs mission was evident within the academics, leadership, and community. Explicitly communicating these elements increased the perceived and actual value of this program both internally and throughout the community
Using stiffness to assess injury risk:comparison of methods for quantifying stiffness and their reliability in triathletes
Background:
A review of the literature has indicated that lower body stiffness, defined as the extent to which the lower extremity joints resists deformation upon contact with the ground, may be a useful measure for assessing Achilles injury risk in triathletes. The nature of overuse injuries suggests that a variety of different movement patterns could conceivably contribute to the final injury outcome, any number and combination of which might be observed in a single individual. Measurements which incorporate both kinetics and kinematics (such as stiffness) of a movement may be better able to shed light on individuals at risk of injury, with further analysis then providing the exact mechanism of injury for the individual. Stiffness can be measured as vertical, leg or joint stiffness to model how the individual interacts with the environment upon landing. However, several issues with stiffness assessments limit the effectiveness of these measures to monitor athletesâ performance and/or injury risk. This may reflect the variety of common biomechanical stiffness calculations (dynamic, time, true leg and joint) that have been used to examine these three stiffness levels (vertical, leg and joint) across a variety of human movements (i.e. running or hopping) as well as potential issues with the reliability of these measures, especially joint stiffness. Therefore, the aims of this study were to provide a comparison of the various methods for measuring stiffness during two forms of human bouncing locomotion (running and hopping) along with the measurement reliability to determine the best methods to assess links with injury risk in triathletes.
Methods:
Vertical, leg and joint stiffness were estimated in 12 healthy male competitive triathletes on two occasions, 7 days apart, using both running at 5.0 msâ1 and hopping (2.2 Hz) tasks.
Results:
Inter-day reliability was good for vertical (ICC = 0.85) and leg (ICC = 0.98) stiffness using the time method. Joint stiffness reliability was poor when assessed individually. Reliability was improved when taken as the sum of the hip, knee and ankle (ICC = 0.86). The knee and ankle combination provided the best correlation with leg stiffness during running (Pearsonâs Correlation = 0.82).
Discussion:
The dynamic and time methods of calculating leg stiffness had better reliability than the âtrueâ method. The time and dynamic methods had the best correlation with the different combinations of joint stiffness, which suggests that they should be considered for biomechanical screening of triathletes. The knee and ankle combination had the best correlation with leg stiffness and is therefore proposed to provide the most information regarding lower limb mechanics during gait in triathletes
Introduction to a New MDPI Open Access Journal: Biomechanics
Biomechanics may be considered a branch of biophysics that involves the application of mechanical principles to better our understanding of the structure, function, and motion of living organisms [...
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