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101.
Score tests for identifying locally dependent item pairs have been proposed for binary item response models. In this article, both the bifactor and the threshold shift score tests are generalized to the graded response model. For the bifactor test, the generalization is straightforward; it adds one secondary dimension associated only with one pair of items. For the threshold shift test, however, multiple generalizations are possible: in particular, conditional, uniform, and linear shift tests are discussed in this article. Simulation studies show that all of the score tests have accurate Type I error rates given large enough samples, although their small‐sample behaviour is not as good as that of Pearson's Χ2 and M2 as proposed in other studies for the purpose of local dependence (LD) detection. All score tests have the highest power to detect the LD which is consistent with their parametric form, and in this case they are uniformly more powerful than Χ2 and M2; even wrongly specified score tests are more powerful than Χ2 and M2 in most conditions. An example using empirical data is provided for illustration.  相似文献   
102.
Church attendance is usually measured in surveys by asking a direct question about frequency of churchgoing over a preset period of time, which is typically a year. Different studies have cast doubt over the validity of this indicator as it tends to overestimate actual attendance to a significant degree. The aim of this article is to compare data on church attendance provided by two different types of research conducted in the United States between 1975 and 2010: survey data (GSS) and data obtained from time use surveys (ATUS). This comparison has three main objectives: (1) to confirm the hypothesis that survey data tend to overestimate actual attendance; (2) to show that this overestimation is not constant over time and space, but tends to vary in an erratic and unpredictable way; and (3) to demonstrate that data provided by time use surveys are more reliable than the frequencies of churchgoing provided by traditional surveys when the objective is to identify trends in religiosity in a population.  相似文献   
103.
Public health care needs to cope with a basic dilemma between providing standardized care within public programmes across entire and at times resource-constrained countries and adapting this care locally when responding to individual needs. This tension between standardization and local adaptation becomes particularly obvious for the prolonged and complicated treatment of multidrug-resistant tuberculosis (MDR-TB). Situated standardization, as introduced by Zuiderent-Jerak [2007a, 2007b] offers a way out of this dilemma. It helps to focus on how standards need to be situated in practice rather than viewing standardization and local adaptation as mutually exclusive practices. How do actors relate standardization and individual care in their practices of treating MDR-TB? Results from qualitative fieldwork at the first MDR-TB treatment sites of the Indian TB programme show that actors situate standards in a particular way. They assess the role of guidelines in a particular situation and on that basis recognize the core recommendations of guidelines or go beyond the guidelines. This allows actors to negotiate how standards should be situated and reconciles the dilemma between local adaptation and standardization. Having guidelines internalized, as is common for Indian TB control, bears both promises and pitfalls for engaging in standardization processes in a situated manner. The results contribute to science and technology study scholarship on guideline development. They highlight how actors coordinate the situating of standards and how this depends upon cultures of control. This illustrates the potential of qualitative studies on local adaptation for guideline developers by revealing existing practices of relating and negotiating local adaptation and standardization.  相似文献   
104.
Traffic density has been shown to be a factor of traffic complexity which influences driver workload. However, little research has systematically varied and examined how traffic density affects workload in dynamic traffic conditions. In this driving simulator study, the effects of two dynamically changing traffic complexity factors (Traffic Flow and Lane Change Presence) on workload were examined. These fluctuations in driving demand were then captured using a continuous subjective rating method and driving performance measures. The results indicate a linear upward trend in driver workload with increasing traffic flow, up to moderate traffic flow levels. The analysis also showed that driver workload increased when a lane change occurred in the drivers’ forward field of view, with further increases in workload when that lane change occurred in close proximity. Both of these main effects were captured via subjective assessment and with driving performance parameters such as speed variation, mean time headway and variation in lateral position. Understanding how these traffic behaviours dynamically influence driver workload is beneficial in estimating and managing driver workload. The present study suggests possible ways of defining the level of workload associated with surrounding traffic complexity, which could help contribute to the design of an adaptive workload estimator.  相似文献   
105.
题组作为众多测验中的一种常见题型,由于项目间存在一定程度的依赖性而违背了局部独立性假设,若用项目反应模型进行参数估计将会出现较大的偏差.题组反应理论将被试与题组的交互作用纳入到模型中,解决了项目间相依性的问题.笔者对题组反应理论的发展、基本原理及其相关研究进行了综述,并将其应用在中学英语考试中.与项目反应理论相对比,结果发现:(1)题组反应模型与项目反应模型在各参数估计值的相关系数较强,尤其是能力参数和难度参数;(2)在置信区间宽度的比较上,题组反应模型在各个参数上均窄于项目反应模型,即题组反应模型的估计精度优于项目反应模型.  相似文献   
106.
Explanations for the cognitive basis of the Müller-Lyer illusion are still frustratingly mixed. To date, Day’s (1989) theory of perceptual compromise has received little empirical attention. In this study, we examine the merit of Day’s hypothesis for the Müller-Lyer illusion by biasing participants toward global or local visual processing through exposure to Navon (1977) stimuli, which are known to alter processing level preference for a short time. Participants (N = 306) were randomly allocated to global, local, or control conditions. Those in global or local conditions were exposed to Navon stimuli for 5 min and participants were required to report on the global or local stimulus features, respectively. Subsequently, participants completed a computerized Müller-Lyer experiment where they adjusted the length of a line to match an illusory-figure. The illusion was significantly stronger for participants with a global bias, and significantly weaker for those with a local bias, compared with the control condition. These findings provide empirical support for Day’s “conflicting cues” theory of perceptual compromise in the Müller-Lyer illusion.  相似文献   
107.
Absolute pitch (AP) is the ability to identify or produce notes without any reference note. An ongoing debate exists regarding the benefits or disadvantages of AP in processing music. One of the main issues in this context is whether the categorical perception of pitch in AP possessors may interfere in processing tasks requiring relative pitch (RP). Previous studies, focusing mainly on melodic and interval perception, have obtained inconsistent results. The aim of the present study was to examine the effect of AP and RP separately, using isolated chords. Seventy-three musicians were categorized into four groups of high and low AP and RP, and were tested on two tasks: identifying chord types (Task 1), and identifying a single note within a chord (Task 2). A main effect of RP on Task 1 and an interaction between AP and RP in reaction times were found. On Task 2 main effects of AP and RP, and an interaction were found, with highest performance in participants with both high AP and RP. Results suggest that AP and RP should be regarded as two different abilities, and that AP may slow down reaction times for tasks requiring global processing.  相似文献   
108.
We have studied the structural, elastic, electronic, phonon and thermodynamic properties of Ir3Ta and Rh3Ta alloys, using ab initio calculations. For the L12 phase, we report the calculated lattice constants, bulk modulus and elastic constants, and these values are compared with previously published values. We also derive the elastic constants from the values of the slopes of the acoustic branches in the phonon dispersion curves. The band structures show that both materials are metallic. The phonon dispersion curves, and their corresponding total and projected densities of states, are obtained using a linear response in the framework of the density functional perturbation theory. The specific heat capacity at constant volume and different temperatures is calculated, and this aspect is discussed using the quasi-harmonic approximation.  相似文献   
109.
Analytic bifactor rotations have been recently developed and made generally available, but they are not well understood. The Jennrich-Bentler analytic bifactor rotations (bi-quartimin and bi-geomin) are an alternative to, and arguably an improvement upon, the less technically sophisticated Schmid-Leiman orthogonalization. We review the technical details that underlie the Schmid-Leiman and Jennrich-Bentler bifactor rotations, using simulated data structures to illustrate important features and limitations. For the Schmid-Leiman, we review the problem of inaccurate parameter estimates caused by the linear dependencies, sometimes called “proportionality constraints,” that are required to expand a p correlated factors solution into a (p + 1) (bi)factor space. We also review the complexities involved when the data depart from perfect cluster structure (e.g., item cross-loading on group factors). For the Jennrich-Bentler rotations, we describe problems in parameter estimation caused by departures from perfect cluster structure. In addition, we illustrate the related problems of (a) solutions that are not invariant under different starting values (i.e., local minima problems) and (b) group factors collapsing onto the general factor. Recommendations are made for substantive researchers including examining all local minima and applying multiple exploratory techniques in an effort to identify an accurate model.  相似文献   
110.
At the synchrotron facility, Super Photon Ring – 8 GeV, in-situ X-ray diffraction during tensile deformation was conducted on ultrafine-grained Cu with a grain size of about 300 nm fabricated by equal-channel angular pressing. The diffraction profile was observed with the time resolution of about 1 s using multiple MYTHEN detectors, and the diffraction angle and the full-width at half-maximum of some Bragg peaks were determined using the pseudo-Voigt function. From the analysis of Bragg peaks, it was found out that there are microscopically three regions; elastic, plastic and transition regions. The 0.2% proof stress obtained from the stress–strain curve locates within the microscopic transition region. Microstrain was evaluated using the Williamson–Hall method and the dislocation density was also obtained from the microstrain. The dislocation density starts increasing before 0.2% proof stress, which is associated with dislocation bow-out and emission from grain boundaries. The Taylor relationship seems to be still satisfied after 0.2% proof stress.  相似文献   
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