Ronna C. Turner

Gender Effect According to Item Directionality on the Perceived Stress Scale for Adults With Multiple Sclerosis

Assessment is critical to rehabilitation practice and research, and self-reports are a commonly used form of assessment. This study examines a gender effect according to item wording on the Perceived Stress Scale for adults with multiple sclerosis. Past studies have demonstrated two-factor solutions on this scale and other scales measuring stress-related constructs with factor loadings being determined by item wording. Moreover, women have typically scored higher on these measured constructs. However, a literature review reveals that this gender difference often manifests only on the factor composed of negatively worded items. This study extends this line of research by examining gender differences on the Perceived Stress Scale on the negatively worded items at both the item and bundle levels after controlling for responses on the positively worded items. Implications of this study on the field of rehabilitation are discussed.

Gender and Perceived Illness Severity Differential Indicators of Employment Concerns for Adults with Multiple Sclerosis

Although research has indicated a link between gender and perceived illness severity and the employment status of people with multiple sclerosis (MS), it has not addressed questions regarding the relationship between those variables and specific types of employment concerns. In this study, a sample of 1,310 adults with MS replied to a mail survey eliciting their concerns regarding employment services and policies. Regardless of perceived severity and gender, adults with MS were dissatisfied with many important employment services and policies. Findings also indicated gender and severity interactions, which are discussed in terms of implications for rehabilitation interventions.

Effects of 28-day Beta-alanine Supplementation on Isokinetic Exercise Performance and Body Composition in Female Masters Athletes

Abstract Glenn, JM, Gray, M, Stewart, RW Jr, Moyen, NE, Kavouras, SA, DiBrezzo, R, Turner, R, Baum, JI, and Stone, MS. Effects of 28-day beta-alanine supplementation on isokinetic exercise performance and body composition in female masters athletes. J Strength Cond Res 30(1): 200–207, 2016—Beta-alanine (BA) supplementation increases exercise performance due to increases in the intramuscular lactate buffer, carnosine. Females are more sensitive to these increases and results are further pronounced in trained individuals. Baseline intramuscular carnosine levels also naturally decrease with age; therefore, trained older females may experience augmented benefits from BA supplementation. However, the ability of BA to increase lower-body isokinetic strength (ISO) in female masters athletes (MA) is unknown. The purpose of this study was to examine the longitudinal effects of BA supplementation on ISO, handgrip strength (HG), and body composition in female MA cyclists. Twenty-two subjects participated in this double-blind randomized study. Subjects were randomized into 2 groups (placebo [PLA] = 8 g dextrose; BA = 800 mg + 8 g dextrose) and supplemented 4 times per day for 28 days. ISO, HG, and body composition were evaluated at baseline and at the same day/time each week over the 28-day intervention. No differences existed between groups at baseline or at the 7, 14, and 21 days time points for any variables (p > 0.05). When evaluating ISO (isokinetic) after 28 days, total work performed during the final third of the assessment (24.0 vs. −16.8% change) in flexion and average peak torque (5.4 vs. 2.9% change) in extension were significantly increased from baseline in BA compared with PLA (p ⩽ 0.05). No differences existed for HG or body composition after supplementation. Twenty-eight days of BA supplementation increased peak torque and work completed, indicating BA improves lower-body exercise performance in female MA.

Effect of hypohydration on thermoregulatory responses in men with low and high body fat exercising in the heat

It is unclear whether men with low body fat (LO-BF) have impaired thermoregulation during exercise heat stress compared with those with high body fat (HI-BF) when euhydration (EU) is maintained. Furthermore, in LO-BF individuals, hypohydration (HY) impairs thermoregulatory responses during exercise heat stress, but it is unknown whether this occurs in HI-BF counterparts. The purpose of this study was to test the hypotheses that men with HI-BF have impaired thermoregulatory responses to exercise heat stress and that HY further exacerbates these impairments vs. LO-BF. Men with LO-BF [n = 11, body mass (BM) 73.9 ± 8.5 kg, BF% 13.6 ± 3.8] and HI-BF (n = 9, BM 89.6 ± 6.9 kg, BF% 30.2 ± 4.1), in a randomized crossover design, performed 60 min of upright cycling in a hot environment (40.3 ± 0.4°C, relative humidity 32.5 ± 1.9%) at a metabolic heat production rate of 6 W/kg BM and finished exercise either euhydrated (EU; 0.3 ± 1.2 vs. 0.3 ± 0.9% BM loss) or HY (-2.5 ± 1.1 vs. -1.7 ± 1.5% BM loss). Changes in rectal temperature (ΔTrec), local sweat rate (ΔLSR), and cutaneous vascular conductance (ΔCVC; %max) were measured throughout. When EU, LO-BF and HI-BF had similar CVC and LSR responses (P > 0.05); however, LO-BF had a lower ΔTrec vs. HI-BF (0.92 ± 0.35 vs. 1.31 ± 0.32°C, P = 0.021). Compared with EU, HY increased end-exercise ΔTrec in LO-BF (0.47 ± 0.37°C, P < 0.01) but not in HI-BF (-0.06 ± 0.29°C, P > 0.05). HY, compared with EU, did not affect ΔLSR and ΔCVC in either group (P > 0.05). We conclude that, when euhydrated, men with HI-BF have a greater increase in Trec vs. LO-BF but similar CVC and LSR. HY exacerbates increases in Trec in LO-BF but not HI-BF. NEW & NOTEWORTHY This is the first known investigation to compare thermoregulatory responses to exercise heat stress between men with high and low body fat (BF) in a physiologically uncompensable environment while simultaneously examining the confounding influence of hydration status. Both groups demonstrated similar sweating and cutaneous vasodilatory responses when euhydrated, despite vast differences in rectal temperature. Furthermore, in contrast to low BF, individuals with high BF demonstrated similar increases in core body temperature when either euhydrated or hypohydrated.

Unidimensional IRT Item Parameter Estimates across Equivalent Test Forms with Confounding Specifications within Dimensions.

When constructing multiple test forms, the number of items and the total test difficulty are often equivalent. Not all test developers match the number of items and/or average item difficulty within subcontent areas. In this simulation study, six test forms were constructed having an equal number of items and average item difficulty overall. Manipulated variables were the number of items and average item difficulty within subsets of items primarily measuring one of two dimensions. Data sets were simulated at four levels of correlation (0, .3, .6, and .9). Item parameters were estimated using the Rasch and two-parameter logistic unidimensional item response theory models. Estimated discrimination and difficulty were compared across forms and to the true item parameters. The average unidimensional estimated discrimination was consistent across forms having the same correlation. Forms having a larger set of easy items measuring one dimension were estimated as being more difficult than forms having a larger set of hard items. Estimates were also investigated within subsets of items, and measures of bias were reported. This study encourages test developers to not only maintain consistent test specifications across forms as a whole but also within subcontent areas.

Differential Item Functioning in rehabilitation research

Measurement is critical to Rehabilitation practice and research. To provide effective services and to have valid research results, it is imperative to have valid and reliable assessment tools. Differential Item Functioning (DIF) is a statistical procedure which better enables us to assess both the validity and the results of measurement instruments. As such, it is a methodology that can be very beneficial to the field of Rehabilitation. The purposes of this article are to (a) explain the fundamental principles and components of DIF, (b) discuss the practical implications of DIF for the Rehabilitation discipline, and (c) provide an example of DIF implementation and interpretation of results.

A Study of Reverse-Worded Matched Item Pairs Using the Generalized Partial Credit and Nominal Response Models

The generalized partial credit model (GPCM) is often used for polytomous data; however, the nominal response model (NRM) allows for the investigation of how adjacent categories may discriminate differently when items are positively or negatively worded. Ten items from three different self-reported scales were used (anxiety, depression, and perceived stress), and authors wrote an additional item worded in the opposite direction to pair with each original item. Sets of the original and reverse-worded items were administered, and responses were analyzed using the two models. The NRM fit significantly better than the GPCM, and it was able to detect category responses that may not function well. Positively worded items tended to be more discriminating than negatively worded items. For the depression scale, category boundary locations tended to have a larger range for the positively worded items than for the negatively worded items from both models. Some pairs of items functioned comparably when reverse-worded, but others did not. If an examinee responds in an extreme category to an item, the same examinee is not necessarily likely to respond in an extreme category at the opposite end of the rating scale to a similar item worded in the opposite direction. Results of this study may support the use of scales composed of items worded in the same direction, and particularly in the positive direction.

Impact of unbalanced DIF item proportions on group-specific DIF identification

Abstract Differences in type I error and power rates for majority and minority groups are investigated when differential item functioning (DIF) contamination in a test is unbalanced. Typically, type I error and power rates are aggregated across groups, however cumulative results can be misleading if subgroups are affected differently by study conditions. With unbalanced DIF contamination, type I error and power rates are reduced for groups with more DIF items favoring them, and increased for groups with less DIF contamination. Even when aggregated impacts appear small, differing subgroup impacts can result in a larger proportional bias than in the original data.

Estimating a unidimensional latent ability across multiple test forms with confounding difficulty and length within sub-content areas

This study investigated the effects of estimating unidimensional latent abilities for subgroups of a population across multiple test forms with confounding difficulty and number of items within sub-content areas. Examinees were grouped based on their true two-dimensional ability; estimates within subgroups were compared across test forms having equal length and average item difficulty overall, but differing numbers of items and/or difficulty within subsets. Examinees with differing true abilities across two dimensions had significantly different estimated scores across forms, depending on the alignment of true ability in each dimension with the number of items and average item difficulty of items within that dimension. These effects tended to decrease as the correlation between dimensions increased. The results of this study bring awareness to test developers for the need of controlling item specifications within sub-content areas.

On the frontline of CCSS implementation: A national study of factors influencing teachers’ perceptions of teaching conditions and job satisfaction

Abstract The Common Core State Standards (CCSS) represent an unprecedented change in American education. As an increasingly integral part of the school accountability movement under No Child Left Behind and Race to the Top, responsibility for implementing CCSS rests largely with school leadership. One important factor in the success or failure of these efforts is the perceptions and experiences of the teachers who will ultimately employ CCSS in the classroom. This survey study examined teachers’ views of CCSS implementation, teaching conditions, collaboration, and job satisfaction. Factor analysis revealed that the openness and activeness of school leadership had a significant effect on teachers’ perceptions of implementation, suggesting that attention to these aspects of leadership is an important consideration during transition to CCSS.