On discretising continuous data for subgroup analysis in baseball pitching and alternative analytical methodologies.

IF 2 3区 医学 Q3 ENGINEERING, BIOMEDICAL
Sports Biomechanics Pub Date : 2024-12-01 Epub Date: 2024-07-09 DOI:10.1080/14763141.2024.2377219
Kevin A Giordano, Kyle W Wasserberger
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引用次数: 0

Abstract

There is a plethora of research attempting to contrast high- and low-velocity pitchers to identify traits to target for increasing velocity. However, pitch velocity exists on a continuum. Therefore, our purpose is to display the analytical discrepancies between creating velocity subgroups and leaving velocity as a continuous variable by examining the influence of ball velocity on elbow valgus torque. Motion capture data for 1315 actively competing pitchers were retrospectively extracted from a private database. We compared three analytic methods: (1) linear regression of valgus torque on ball velocity, (2) t-test between low- and high-velocity groups formed by a median split, and (3) t-test between very low- and very high-velocity groups formed by upper and lower velocity quartiles. Linear regression indicates ball velocity influenced valgus torque (p < 0.001, R2 = 0.280). Median splitting reduced the predictability of ball velocity on valgus torque (p < 0.001, R2 = 0.180). Conversely, extreme group splitting artificially inflated the effect size (p < 0.001, R2 = 0.347). We recommend sports biomechanics researchers not discretise a continuous variable to form subgroups for analysis because (1) it distorts the relationship between the variables of interest and (2) a regression equation can be used to estimate the dependent variable at any value of the independent variable, not just the group means.

棒球投球中用于分组分析的连续数据离散化及替代分析方法。
有大量研究试图对比高投速和低投速投手,以确定提高投速的目标特征。然而,投球速度是一个连续体。因此,我们的目的是通过研究球速对肘外翻力矩的影响,来显示创建速度分组与将速度作为连续变量之间的分析差异。我们从一个私人数据库中回顾性地提取了 1315 名积极参加比赛的投手的运动捕捉数据。我们比较了三种分析方法:(1)肘外翻力矩对球速的线性回归;(2)以中位数划分的低速组和高速组之间的 t 检验;以及(3)以上下速度四分位数划分的极低速组和极高速组之间的 t 检验。线性回归结果表明,球速对外翻力矩有影响(p 2 = 0.280)。中位数拆分降低了球速对外翻扭矩的可预测性(p 2 = 0.180)。相反,极端分组则人为地扩大了效应大小(p 2 = 0.347)。我们建议运动生物力学研究人员不要将连续变量离散化以形成分组进行分析,因为(1)这样做会扭曲相关变量之间的关系;(2)回归方程可用于估计因变量在自变量的任何值上的影响,而不仅仅是分组平均值。
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来源期刊
Sports Biomechanics
Sports Biomechanics 医学-工程:生物医学
CiteScore
5.70
自引率
9.10%
发文量
135
审稿时长
>12 weeks
期刊介绍: Sports Biomechanics is the Thomson Reuters listed scientific journal of the International Society of Biomechanics in Sports (ISBS). The journal sets out to generate knowledge to improve human performance and reduce the incidence of injury, and to communicate this knowledge to scientists, coaches, clinicians, teachers, and participants. The target performance realms include not only the conventional areas of sports and exercise, but also fundamental motor skills and other highly specialized human movements such as dance (both sport and artistic). Sports Biomechanics is unique in its emphasis on a broad biomechanical spectrum of human performance including, but not limited to, technique, skill acquisition, training, strength and conditioning, exercise, coaching, teaching, equipment, modeling and simulation, measurement, and injury prevention and rehabilitation. As well as maintaining scientific rigour, there is a strong editorial emphasis on ''reader friendliness''. By emphasising the practical implications and applications of research, the journal seeks to benefit practitioners directly. Sports Biomechanics publishes papers in four sections: Original Research, Reviews, Teaching, and Methods and Theoretical Perspectives.
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