Going Beyond Convergence in Bayesian Estimation: Why Precision Matters Too and How to Assess It     

Steffen Zitzmann  Martin Hecht 《Structural equation modeling》2019,26(4):646-661

Most of the software that is available to implement Bayesian approaches uses Markov chain Monte Carlo (MCMC) methods. It is our impression that many researchers are primarily concerned with convergence as assessed by the Potential Scale Reduction (PSR) and that other aspects of MCMC are largely ignored. In this article, we argue that the precision with which the Bayesian estimates are approximated by summary statistics for the MCMC chain is essential to ensure good statistical properties. We discuss the Effective Sample Size (ESS), which indicates how well an estimate is approximated, and present evidence from two simulation studies and an example from organizational research to support our claim that researchers should be concerned not only with convergence but also with precision, particularly when a multilevel model is estimated. In addition, we demonstrate how Mplus can be modified so that users can control the ESS, and we conclude with recommendations.  相似文献   

Differentiation and social selectivity in German higher education     

Steffen Schindler  David Reimer 《Higher Education》2011,61(3):261-275

In this paper we investigate social selectivity in access to higher education in Germany and, unlike most previous studies, explicitly devote attention to semi-tertiary institutions such as the so-called universities of cooperative education. Drawing on rational choice models of educational decisions we seek to understand which factors influence upper secondary graduates from different social backgrounds in their choices of diverse tertiary institutions in Germany. We find that scholastic performance, expected job security, study duration, monetary costs and preferences for study content considerably contribute to the creation of socially selective choice patterns of post-secondary careers. The characteristics of semi-tertiary institutions—such as universities of cooperative education that combine firm-based training with tertiary education—constitute a potential alternative that could reduce inequities in access to higher learning.  相似文献   

Open wedge re-correction high tibial osteotomy in an elderly patient with a varus angulated non-united dome-shaped high tibial osteotomy     

Steffen Schröter  Lukas Konstantinidis  Tobias M. Kraus  Fabian Stuby  Ulrich Stöckle  Thomas Freude 《Journal of Zhejiang University. Science. B》2013,14(11):1054-1058

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Die Körperzusammensetzung von Hobbygamern im Vergleich zu deutschlandweit erhobenen Referenzdaten     

Steffen C. E. Schmidt  Filip Kowal  Alexander Woll 《Sportwissenschaft》2018,48(3):438-446

About two thirds of adults in Germany are overweight or obese. While an increase in the consumption of high-calorie food is considered the main cause, the influence of various forms of sedentary activities is still controversially discussed. The aim of the present study is to compare the body composition of hobby gamers with reference data collected throughout Germany and to examine the effects of intensive use of computer games (gaming) on body composition. A total of 68 male participants of a computer game event aged 18–46 years (27.9 years; 180.1?cm; 83.5?kg; BMI 25.7) were examined for fat mass, body cell mass, extracellular mass, body water and phase angle using bioelectrical impedance analysis (BIA, Nutriguard MS type, data input). Ten test persons were retested by means of segmental 8?electrode BIA after a 24?h interval during their visit to the event. As a reference sample, data from 278 male adults of the same age (27.9 years, 179.4?cm; 78.8?kg; BMI 24.5) were collected in 168 locations throughout Germany. The hobby gamers reported on average 37.1?h screen media usage per week. Compared to the reference sample, they showed a slightly higher body cell mass index (p?<?0.01, T?=?4.07), but no differences in fat mass index (p?=?0.96, T?=?0.05) and phase angle (p?=?0.90, T?=?0.12). A significant increase in body water (T₀: 48.2?l, T₀₊₂₄?_h: 49.3?l; p?=?0.04, T?=?2.39) and decrease in the phase angle of the lower extremities (T₀:?7.40, T₀₊₂₄?_h: ?6.85; p?<?0.01, T?=?5.40) was observed in the 24?h retest. Compared to the reference data collected throughout Germany, hobby gamers show no differences in health-relevant parameters of body composition. Nevertheless, after intensive gaming, a short-term increase in the amount of extracellular water in the lower extremities was found. Due to these disturbances in the water balance, the consequent execution of movement breaks during gaming is important.  相似文献   

The Active Tradition: A Convergence of Ideas     

Alan Steffen 《Educational theory》1973,23(4):321-332

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‘Whys’ and ‘Hows’ of Using Philosophy in Mathematics Education     

Uffe Thomas Jankvist  Steffen Møllegaard Iversen 《Science & Education》2014,23(1):205-222

The article elaborates and exemplifies a potential categorization of the reasons for using philosophy, in particular the philosophy of mathematics, in mathematics education and approaches to doing so—the so-called ‘whys’ and ‘hows’. More precisely, the ‘whys’ are divided into the two categories of ‘philosophy as a tool’ for teaching and learning mathematics, and ‘philosophy as a goal’, referring to a stance of considering it a purpose in itself to teach students certain aspects regarding the philosophy of mathematics. A division of the ‘hows’ into three different categories is offered: illumination approaches; modules approaches; and philosophy-based approaches. A major part of the article is spent on providing illustrative exemplifications of each of these approaches by referring to already implemented uses of philosophy of mathematics in mathematics education as well as by suggesting new ones.  相似文献   

Exploring data management content in doctoral nursing handbooks     

Rebecca Raszewski  Abigail H. Goben  Martha Dewey Bergren  Krista Jones  Catherine Ryan  Alana Steffen  Susan C. Vonderheid 《Journal of the Medical Library Association》2021,109(2):248

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.  相似文献   

Explaining Scientists’ Plans for International Mobility from a Life Course Perspective     

Nicolai Netz  Steffen Jaksztat 《Research in higher education》2017,58(5):497-519

We identify factors influencing young scientists’ plans for research stays abroad by embedding theories of social inequality, educational decision making, and migration into a life course framework. We test the developed model of international academic mobility by calculating a structural equation model using data from an online survey of scientists employed at German universities below the rank of full professor. We find that earlier international mobility mobilises scientists to plan a research stay abroad. This turns out to be a potential channel of social inequality reproduction, as individuals from a high social origin in particular spend time abroad in their early life course. Moreover, scientists’ research contexts play a vital role: Internationalised institutional environments and academic disciplines as well as personal international networks create opportunity structures that ease research stays abroad. Similarly, the current social context matters: Parenthood decreases the likelihood of plans for international mobility among female scientists. This may entail long-lasting gender inequalities. Finally, young scientists striving for an academic career are more likely to plan a research stay abroad than those with exit plans. Our results show that beyond the current context, both past life events and future life goals shape scientists’ decisions about international mobility.  相似文献   

King Kong,Storks and Birth Rates     

Steffen Wirth 《Teaching Statistics》2003,25(1):29-32

This article discusses the influence extreme observations can exert on linear correlation between variables. It shows that standard p‐values obtained according to ordinary least squares and median regression can be misleading. Bootstrapping can prevent underestimation of the standard error of the regression coefficient and therefore unmask the deceiving correlation.  相似文献