Using Wherry's Adjusted R 2 and Mallow's Cp for Model Selection From All Possible Regressions

Selecting a subset of predictors from a pool of potential predictors continues to be a common problem encountered by applied researchers in education. Because of several limitations associated with stepwise variable selection procedures, the examination of all possible regression solutions has been recommended. The authors evaluated the use of Mallow's C_p and Wherry's adjusted R ² statistics to select a final model from a pool of model solutions. Neither the C_p nor the adjusted R ² statistic correctly identified the underlying regression model any better and was generally worse than the stepwise selection method, which itself was poor. Using any of the model selection procedures studied here resulted in biased estimates of the authentic regression coefficients and underestimation of their standard errors. The use of theory and professional judgment is recommended for the selection of variables in a prediction equation.     

Listening Competence in Initial Interactions II: Applying Trait Centrality to Discover the Relative Placement of Listening Competence Among Implicit Competency Theories

This article explores the relative placement of listening competence within other implicit theories used to form judgments of interlocutor competence. Two studies explore the relations among communicative competence, social skills, and listening competence and various attributes that are purportedly implied by each. Study 1 reveals that very few attributes are uniquely related to any one implicit theory. Study 2 demonstrates that listening competence is located subordinately to communicative competence. The discussion focuses on what these studies add to the competency literature and how future research can continue to explore implicit competency theories.     

Physiological demands of downhill mountain biking

Abstract

Mountain biking is a popular recreational pursuit and the physiological demands of cross-country style riding have been well documented. However, little is known regarding the growing discipline of gravity-assisted downhill cycling. We characterised the physiological demands of downhill mountain biking under typical riding conditions. Riding oxygen consumption ([Vdot]O₂) and heart rate (HR) were measured on 11 male and eight female experienced downhill cyclists and compared with data during a standardised incremental to maximum ([Vdot]O_2max) exercise test. The mean [Vdot]O₂ while riding was 23.1 ± 6.9 ml · kg^?1 · min^?1 or 52 ± 14% of [Vdot]O_2max with corresponding heart rates of 146 ± 11 bpm (80 ± 6% HRmax). Over 65% of the ride was in a zone at or above an intensity level associated with improvements in health-related fitness. However, the participants’ heart rates and ratings of perceived exertion were artificially inflated in comparison with the actual metabolic demands of the downhill ride. Substantial muscular fatigue was evident in grip strength, which decreased 5.4 ± 9.4 kg (5.5 ± 11.2%, P = 0.03) post-ride. Participation in downhill mountain biking is associated with significant physiological demands, which are in a range associated with beneficial effects on health-related fitness.     

The effect of consistent and varied follow-through practice schedules on learning a table tennis backhand

In table tennis the follow-through action after a shot is an important part of skill execution. In this experiment, we aimed to extend literature around the contextual interference effect by investigating whether the way the follow-through is organised in practice affects learning of the backhand shot in table tennis. Thirty unskilled participants were allocated to blocked-variable practice, random-variable practice or a control-constant group and aimed backhand shots towards a target following ball projection from a machine. Each group completed these shots in a pre-test, a training phase with follow-through manipulations, a post-test, and a retention test. The random-variable group improved their shot accuracy from pre-test to post-test and from pre-test to retention test (both P < 0.01, d = 1.03), whereas neither the blocked-variable nor the control-constant group displayed any change in shot accuracy. Practising the follow-through in a random-variable fashion enhanced learning of the preceding shot compared with blocked-variable practice or no follow-through instructions. The benefits of learning motor skills under conditions of high contextual interference also apply to how follow-through actions are organised. The findings are valuable to coaches and suggest that instructions related to the follow-through action should be considered as well as the primary skill itself.     

Prekindergarten Interactive Book Reading Quality and Children’s Language and Literacy Development: Classroom Organization as a Moderator

Research Findings: This study examined the association between interactive book reading quality and prekindergarten children’s gains in language and literacy skills over the course of an academic year for 96 teachers and 417 children across multiple locations in the United States. Two moderators were examined, namely, children’s initial skill level and teachers’ classroom organization during an interactive read-aloud session. In keeping with prior research, interactive book reading quality, measured by examination of teachers’ extratextual talk, was positively and significantly related to children’s development of both language and literacy skills. Interactive book reading quality was not significantly moderated by children’s initial skills, with the exception that interactive book reading quality appeared most beneficial to children’s print knowledge for children entering prekindergarten with relatively low skill. The unique contribution of this study is that the association between interactive book reading quality and children’s expressive vocabulary was dependent on an organized classroom during the book reading session. Practice or Policy: The quality of teachers’ talk during interactive book reading may matter for children’s vocabulary development only when reading sessions are characterized by relatively high classroom organization. Classroom organization should be an important consideration while planning for interactive book reading sessions.     

Teaching Artistry and Workplace Wellness

How can Applied Theatre impact office productivity and employee well-being? A pilot program in NYC presents its discoveries.