On discretising continuous data for subgroup analysis in baseball pitching and alternative analytical methodologies
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 leavin...
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Published in | Sports biomechanics pp. 1 - 12 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
England
09.07.2024
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Subjects | |
Online Access | Get full text |
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Summary: | 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 (
< 0.001, R
= 0.280). Median splitting reduced the predictability of ball velocity on valgus torque (
< 0.001, R
= 0.180). Conversely, extreme group splitting artificially inflated the effect size (
< 0.001, R
= 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. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1476-3141 1752-6116 1752-6116 |
DOI: | 10.1080/14763141.2024.2377219 |