An Exercise to Introduce Power

In introductory statistics courses, the concept of power is usually presented in the context of testing hypotheses about the population mean. We instead propose an exercise that uses a binomial probability table to introduce the idea of power in the context of testing a population proportion.     

Body mass changes during training in elite rugby union: Is a single test of hydration indices reliable?

There is limited research studying fluid and electrolyte balance in rugby union players, and a paucity of information regarding the test–retest reliability. This study describes the fluid balance of elite rugby union players across multiple squads and the reliability of fluid balance measures between two equivalent training sessions. Sixty-one elite rugby players completed a single fluid balance testing session during a game simulation training session. A subsample of 21 players completed a second fluid balance testing session during an equivalent training session. Players were weighed in minimal clothing before and after each training session. Each player was provided with their own drinks which were weighed before and after each training session. More players gained body weight (9 (14.8%)) during training than lost greater than 2% of their initial body mass (1 (1.6%)). Pre-training body mass and rate of fluid loss were significantly associated (r?=?0.318, p?=?.013). There was a significant correlation between rate of fluid loss in sessions 1 (1.74?±?0.32?L?h^?1) and 2 (1.10?±?0.31?L.?h^?1), (r?=?0.470, p?=?.032). This could be useful for nutritionists working with rugby squads to identify players with high sweat losses.     

Recovery Responses to Maximal Exercise in Healthy-Weight Children and Children With Obesity

Purpose: The purpose of this study was to examine differences in heart rate recovery (HRRec) and oxygen consumption recovery (VO₂ recovery) between young healthy-weight children and children with obesity following a maximal volitional graded exercise test (GXTmax). Method: Twenty healthy-weight children and 13 children with obesity completed body composition testing and performed a GXTmax. Immediately after the GXTmax, HRRec and VO₂ recovery were measured each minute for 5 consecutive minutes. Results: There were no statistically significant group differences in HRRec for the 5 min following maximal exercise, Wilks’s Lambda = .885, F(4, 28) = 0.911, p = .471, between the healthy-weight children and children with obesity despite statistically significant differences in body fat percentage (BF%; healthy-weight children, 18.5 ± 6.1%; children with obesity, 41.1 ± 6.9%, p < .001) and aerobic capacity relative to body mass (VO₂ peak; healthy-weight children, 46.8 ± 8.2 mL/kg/min; children with obesity, 31.9 ± 4.7 mL/kg/min, p < .001). There were statistically significant differences in VO₂ recovery for the 5 min following exercise, Wilks’s Lambda = .676, F(4, 26) = 3.117, p = .032. There were no statistically significant correlations between HRRec and body mass index (BMI), BF%, VO₂peak, or physical activity. Conclusions: In a healthy pediatric population, obesity alone does not seem to significantly impact HRRec, and because HRRec was not related to obesity status, BMI, or BF%, it should not be used as the sole indicator of aerobic capacity or health status in children. Using more than one recovery variable (i.e., HRRec and VO₂ recovery) may provide greater insight into cardiorespiratory fitness in this population.     

The multiple deficit model of dyslexia: what does it mean for identification and intervention?

Research demonstrates that phonological skills provide the basis of reading acquisition and are a primary processing deficit in dyslexia. This consensus has led to the development of effective methods of reading intervention. However, a single phonological deficit is not sufficient to account for the heterogeneity of individuals with dyslexia, and recent research provides evidence that supports a multiple-deficit model of reading disorders. Two studies are presented that investigate (1) the prevalence of phonological and cognitive processing deficit profiles in children with significant reading disability and (2) the effects of those same phonological and cognitive processing skills on reading development in a sample of children that received treatment for dyslexia. The results are discussed in the context of implications for identification and an intervention approach that accommodates multiple deficits within a comprehensive skills-based reading program.     

Failure-to-thrive, maltreatment and the behavior and development of 6-year-old children from low-income, urban families: a cumulative risk model

OBJECTIVE: A cumulative risk model was used to examine the relationship among failure-to-thrive (FTT), maltreatment, and four aspects of children's development: cognitive performance (standardized testing), adaptive functioning at school, and classroom behavior (teacher report), and behavior at home (maternal report). METHOD: The sample included 193 6-year-old children and their families, recruited from pediatric clinics serving inner-city, low-income, primarily African-American families, who were part of a longitudinal investigation of child development and maltreatment. Four risk groups were formed based on their growth and maltreatment history: neither FTT nor Maltreatment, FTT Only, Maltreatment Only, and both FTT and Maltreatment. FTT was defined as a deceleration in weight gain (weight-for-age below the 5th percentile) prior to 25 months of age among children born at term with birth weight appropriate for gestational age. Maltreatment was defined as having at least one report to CPS for neglect, physical abuse and/or sexual abuse. RESULTS: Risk status was negatively associated with each of the four developmental outcomes. Children with a history of both FTT and maltreatment had more behavior problems and worse cognitive performance and school functioning than children with neither risk factor. Children with only one risk factor (either FTT or maltreatment) achieved intermediate scores. CONCLUSIONS: Findings support a cumulative risk model as being more detrimental to children's development than the presence of a single risk factor alone, consistent with theories linking the accumulation of environmental risks to negative consequences. These results underscore the importance of interventions to prevent both FTT and maltreatment during children's early years.     

Stability of arithmetic disability subtypes

Cross-sectional research has identified subtypes of children with learning disabilities who may have distinctive cognitive ability patterns. This study examined the stability over 19 months of academic subtyping classifications for 80 children ages 9 to 13 representing four subtypes of arithmetic disabilities (AD), using three criteria for learning disability identification. Approximately half of the sample retained AD regardless of identification method. Children with pervasive deficits in arithmetic, reading, and spelling displayed the greatest subtype stability. Only one third of the children with the other subtypes, including those with isolated arithmetic deficits, retained their original subtypes. Thus, drawing conclusions and making recommendations based on academic subtyping at a single point in time may be unwise.