Not quite normal: Consequences of violating the assumption of normality in regression mixture models

Regression mixture models are a new approach for finding differential effects which have only recently begun to be used in applied research. This approach comes at the cost of the assumption that error terms are normally distributed within classes. The current study uses Monte Carlo simulations to explore the effects of relatively minor violations of this assumption, the use of an ordered polytomous outcome is then examined as an alternative which makes somewhat weaker assumptions, and finally both approaches are demonstrated with an applied example looking at differences in the effects of family management on the highly skewed outcome of drug use. Results show that violating the assumption of normal errors results in systematic bias in both latent class enumeration and parameter estimates. Additional classes which reflect violations of distributional assumptions are found. Under some conditions it is possible to come to conclusions that are consistent with the effects in the population, but when errors are skewed in both classes the results typically no longer reflect even the pattern of effects in the population. The polytomous regression model performs better under all scenarios examined and comes to reasonable results with the highly skewed outcome in the applied example. We recommend that careful evaluation of model sensitivity to distributional assumptions be the norm when conducting regression mixture models.     

水合作用与身体活动：科学概念及实际应用

有关脱水对身体活动的影响 ,你们已经进行了哪些研究 ?Mack:我们的研究集中于脱水的两个方面。首先 ,我们测试了脱水对身体在热负荷下散热能力的危害。这些研究主要想弄明白由脱水造成的低钠血症和高渗透压 ,限制热从体内传输到皮肤 ,并降低热量从皮肤散发到周围的生理机制。我们的研究也发现压力反射机制对皮肤血流量的调节和受中心血量变化影响的发汗反应 ,以及血浆渗透压增高抑制热出汗的特点。其次 ,我们还测试了所谓的“不自主脱水”现象。在这些研究中 ,我们测试了身体的总水分下降后 ,体液完全恢复的延迟机制。我们的工作是想知道造…     

The relation of self-efficacy measures to sport performance: a meta-analytic review

This meta-analysis examined the relationship between self-efficacy and performance in sport. Based on 45 studies (102 correlations), the average correlation between self-efficacy and sport performance was .38. Given the heterogeneity of findings, follow-up univariate and multivariate moderator analyses were conducted. Results indicated that the most important moderator was concordance, thereby highlighting the importance of matching the self-efficacy and performance measures. Additional moderators we examined included the types of self-efficacy measures, the types of performance measures, the nature of the task, and the time of assessments. These variables accounted for approximately 44% of the variance in the self-efficacy-performance relationship. Practical implications of the findings are discussed.     

The data life cycle applied to our own data

Increased demand for data-driven decision making is driving the need for librarians to be facile with the data life cycle. This case study follows the migration of reference desk statistics from handwritten to digital format. This shift presented two opportunities: first, the availability of a nonsensitive data set to improve the librarians'' understanding of data-management and statistical analysis skills, and second, the use of analytics to directly inform staffing decisions and departmental strategic goals. By working through each step of the data life cycle, library faculty explored data gathering, storage, sharing, and analysis questions.     

Exploring data management content in doctoral nursing handbooks

Objective:While data management (DM) is an increasing responsibility of doctorally prepared nurses, little is understood about how DM education and expectations are reflected within student handbooks. The purpose of this study was to assess the inclusion of DM content within doctoral nursing student handbooks.Methods:A list of 346 doctoral programs was obtained from the American Association of Colleges of Nursing (AACN). Program websites were searched to locate program handbooks, which were downloaded for analysis. A textual review of 261 handbooks from 215 institutions was conducted to determine whether DM was mentioned and, if so, where the DM content was located. Statistical analysis was performed to compare the presence of DM guidance by type of institution, Carnegie Classification, and the type of doctoral program handbook.Results:A total of 1,382 codes were identified across data life cycle stages, most commonly in the handbooks’ project requirements section. The most frequent mention of DM was in relation to collecting and analyzing data; the least frequent related to publishing and sharing data and preservation. Significant differences in the frequency and location of codes were identified by program type and Carnegie Classification.Conclusions:Nursing doctoral program handbooks primarily address collecting and analyzing data during student projects. Findings suggest limited education about, and inclusion of, DM life cycle content, especially within DNP programs. Collaboration between nursing faculty and librarians and nursing and library professional organizations is needed to advance the adoption of DM best practices for preparing students in their future roles as clinicians and scholars.     

Taking Children Seriously

One of the timeless messages of early childhood education is to treat children with respect and value their unique perspectives on the world. This editorial tells the stories of three young children who wanted to be helpful and accept responsibility. It also tells the story of three professionals who identified with the child and responded supportively.