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The equality of two group variances is frequently tested in experiments. However, criticisms of null hypothesis statistical testing on means have recently arisen and there is interest in other types of statistical tests of hypotheses, such as superiority/non-inferiority and equivalence. Although these tests have become more common in psychology and social sciences, the corresponding sample size estimation for these tests is rarely discussed, especially when the sampling unit costs are unequal or group sizes are unequal for two groups. Thus, for finding optimal sample size, the present study derived an initial allocation by approximating the percentiles of an F distribution with the percentiles of the standard normal distribution and used the exhaustion algorithm to select the best combination of group sizes, thereby ensuring the resulting power reaches the designated level and is maximal with a minimal total cost. In this manner, optimization of sample size planning is achieved. The proposed sample size determination has a wide range of applications and is efficient in terms of Type I errors and statistical power in simulations. Finally, an illustrative example from a report by the Health Survey for England, 1995–1997, is presented using hypertension data. For ease of application, four R Shiny apps are provided and benchmarks for setting equivalence margins are suggested.  相似文献   
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As a core component of most cognitive diagnosis models, the Q-matrix, or item and attribute association matrix, is typically developed by domain experts, and tends to be subjective. It is critical to validate the Q-matrix empirically because a misspecified Q-matrix could result in erroneous attribute estimation. Most existing Q-matrix validation procedures are developed for dichotomous responses. However, in this paper, we propose a method to empirically detect and correct the misspecifications in the Q-matrix for graded response data based on the sequential generalized deterministic inputs, noisy ‘and’ gate (G-DINA) model. The proposed Q-matrix validation procedure is implemented in a stepwise manner based on the Wald test and an effect size measure. The feasibility of the proposed method is examined using simulation studies. Also, a set of data from the Trends in International Mathematics and Science Study (TIMSS) 2011 mathematics assessment is analysed for illustration.  相似文献   
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Disengaged test taking tends to be most prevalent with low-stakes tests. This has led to questions about the validity of aggregated scores from large-scale international assessments such as PISA and TIMSS, as previous research has found a meaningful correlation between the mean engagement and mean performance of countries. The current study, using data from the computer-based version of the PISA-Based Test for Schools, examined the distortive effects of differential engagement on aggregated school-level scores. The results showed that, although there was considerable differential engagement among schools, the school means were highly stable due to two factors. First, any distortive effects of disengagement in a school were diluted by a high proportion of the students exhibiting no non-effortful behavior. Second, and most interestingly, disengagement produced both positive and negative distortion of individual student scores, which tended to cancel out much of the net distortive effect on the school’s mean.  相似文献   
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An Implicit Association Test was developed to assess the mental illness stigma in people from the general population, mental health professionals, people with a diagnosis, and family members. No differences were found between groups. Implicit stigma was found throughout the sample, with lower scores in the younger age group.  相似文献   
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In the bioethical literature, discrimination in insurance on the basis of genetic risk factors detected by genetic testing has been defended and opposed on various ethical grounds. One important argument in favour of the practice is offered by those who believe that it is not possible to distinguish between genetic and non-genetic information, at least not for practical policy purposes such as insurance decision-making. According to the argument from indistinguishability, the use of genetic test information for insurance purposes should be permitted, because genetic test information is no different from non-genetic medical information in any relevant respect, therefore it would be inconsistent to prohibit the former whilst permitting the latter. This paper discusses and defends this argument and suggests a new, more tenable foundation.  相似文献   
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Two new tests for a model for the response times on pure speed tests by Rasch (1960) are proposed. The model is based on the assumption that the test response times are approximately gamma distributed, with known index parameters and unknown rate parameters. The rate parameters are decomposed in a subject ability parameter and a test difficulty parameter. By treating the ability as a gamma distributed random variable, maximum marginal likelihood (MML) estimators for the test difficulty parameters and the parameters of the ability distribution are easily derived. Also the model tests proposed here pertain to the framework of MML. Two tests or modification indices are proposed. The first one is focused on the assumption of local stochastic independence, the second one on the assumption of the test characteristic functions. The tests are based on Lagrange multiplier statistics, and can therefore be computed using the parameter estimates under the null model. Therefore, model violations for all items and pairs of items can be assessed as a by-product of one single estimation run. Power studies and applications to real data are included as numerical examples.  相似文献   
28.
The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.  相似文献   
29.
探讨平板运动试验(TET)结合颈动脉斑块检测在诊断冠心病的临床意义。对166例疑诊冠心病患者进行冠状动脉造影(CAG),TET,颈动脉斑块检查,以CAG的诊断结果为金标准,分析TET,颈动脉斑块检查,TET结合颈动脉斑块检查诊断冠心病的敏感度、特异度。比较三者诊断冠心病的敏感度、特异度。三者敏感度分别为71.4%、64.3%、96.0%。特异度分别为65%、60.0%、82.4%。后者较前两者敏感度、特异度P<0.05。TET结合颈动脉斑块检查可显著提高冠心病的诊断率,不失为CAG前的筛选方法。  相似文献   
30.
护士职业的人格特质研究   总被引:21,自引:1,他引:21  
采用Y-G性格测验问卷,对临床护士和在读护生共390人,进行了心理测评,展开了护士职业的人格特质研究。研究结果表明:优秀护士群体的性格类型和某些人格特质显著地优于一般护士群体;优秀护士与一般护士间所显现出显著差异的人格特质,对于护士角色人格的构成具有决定性影响;Y-G性格测验的A型性格类型评定对于护士职业的心理选拔显现特异性趋势;整个测评研究结果,基本支持"护士个体人格特质与角色人格特质的匹配模式"等理论假设.  相似文献   
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