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李大林 《柳州职业技术学院学报》2010,10(4):39-41
研究复数域上亏损矩阵的广义特征向量。根据广义特征子空间链,提出广义特征向量组的广义线性相关与广义线性无关的概念,用以刻画若当链的计算复杂性。 相似文献
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ABSTRACTThis study examined the effect of similar vs. dissimilar proficiency distributions on uniform DIF detection on a statewide eighth grade mathematics assessment. Results from the similar- and dissimilar-ability reference groups with an SWD focal group were compared for four models: logistic regression, hierarchical generalized linear model (HGLM), the Wald-1 IRT-based test, and the Mantel-Haenszel procedure. A DIF-free-then-DIF strategy was used. The rate of DIF detection was examined among all accommodated scores and common accommodation subcategories. No items were detected for DIF using the similar ability distribution reference group, regardless of method. With the dissimilar ability reference group, logistic regression and Mantel–Haenszel flagged 8–17%, and the Wald-1 and HGLM test flagged 23–38% of items for DIF. Forming focal groups by accommodation type did not alter the pattern of DIF detection. Creating a reference group to be similar in ability to the focal group may control the rate of erroneous DIF detection for SWD. 相似文献
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Seock-Ho Kim Allan S. Cohen Cigdem Alagoz Sukwoo Kim 《Journal of Educational Measurement》2007,44(2):93-116
Data from a large-scale performance assessment ( N = 105,731) were analyzed with five differential item functioning (DIF) detection methods for polytomous items to examine the congruence among the DIF detection methods. Two different versions of the item response theory (IRT) model-based likelihood ratio test, the logistic regression likelihood ratio test, the Mantel test, and the generalized Mantel–Haenszel test were compared. Results indicated some agreement among the five DIF detection methods. Because statistical power is a function of the sample size, the DIF detection results from extremely large data sets are not practically useful. As alternatives to the DIF detection methods, four IRT model-based indices of standardized impact and four observed-score indices of standardized impact for polytomous items were obtained and compared with the R 2 measures of logistic regression. 相似文献
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The assessment of differential item functioning (DIF) in polytomous items addresses between-group differences in measurement properties at the item level, but typically does not inform which score levels may be involved in the DIF effect. The framework of differential step functioning (DSF) addresses this issue by examining between-group differences in the measurement properties at each step underlying the polytomous response variable. The pattern of the DSF effects across the steps of the polytomous response variable can assume several different forms, and the different forms can have different implications for the sensitivity of DIF detection and the final interpretation of the causes of the DIF effect. In this article we propose a taxonomy of DSF forms, establish guidelines for using the form of DSF to help target and guide item content review and item revision, and provide procedural rules for using the frameworks of DSF and DIF in tandem to yield a comprehensive assessment of between-group measurement equivalence in polytomous items. 相似文献
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广义逆矩阵与线性方程组的解 总被引：2，自引：0，他引：2
周金森 《Journal of Zhangzhou Technical Institute》2006,8(2):15-17
本文给出了各种广义逆矩阵的定义、性质及计算方法,并用广义逆矩阵来表示线性方程组的各种不同解。 相似文献
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Randall D. Penfield 《Journal of Educational Measurement》2010,47(2):129-149
In this article, I address two competing conceptions of differential item functioning (DIF) in polytomously scored items. The first conception, referred to as net DIF, concerns between-group differences in the conditional expected value of the polytomous response variable. The second conception, referred to as global DIF, concerns the conditional dependence of group membership and the polytomous response variable. The distinction between net and global DIF is important because different DIF evaluation methods are appropriate for net and global DIF; no currently available method is universally the best for detecting both net and global DIF. Net and global DIF definitions are presented under two different, yet compatible, modeling frameworks: a traditional item response theory (IRT) framework, and a differential step functioning (DSF) framework. The theoretical relationship between the IRT and DSF frameworks is presented. Available methods for evaluating net and global DIF are described, and an applied example of net and global DIF is presented. 相似文献
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One approach to measuring unsigned differential test functioning is to estimate the variance of the differential item functioning (DIF) effect across the items of the test. This article proposes two estimators of the DIF effect variance for tests containing dichotomous and polytomous items. The proposed estimators are direct extensions of the noniterative estimators developed by Camilli and Penfield (1997) for tests composed of dichotomous items. A small simulation study is reported in which the statistical properties of the generalized variance estimators are assessed, and guidelines are proposed for interpreting values of DIF effect variance estimators. 相似文献
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Haiwen Chen 《Journal of Educational Measurement》2012,49(3):269-284
In this article, linear item response theory (IRT) observed‐score equating is compared under a generalized kernel equating framework with Levine observed‐score equating for nonequivalent groups with anchor test design. Interestingly, these two equating methods are closely related despite being based on different methodologies. Specifically, when using data from IRT models, linear IRT observed‐score equating is virtually identical to Levine observed‐score equating. This leads to the conclusion that poststratification equating based on true anchor scores can be viewed as the curvilinear Levine observed‐score equating. 相似文献
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Detection of differential item functioning (DIF) is most often done between two groups of examinees under item response theory. It is sometimes important, however, to determine whether DIF is present in more than two groups. In this article we present a method for detection of DIF in multiple groups. The method is closely related to Lard's chi-square for comparing vectors of item parameters estimated in two groups. An example using real data is provided. 相似文献
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To assess item dimensionality, the following two approaches are described and compared: hierarchical generalized linear model (HGLM) and multidimensional item response theory (MIRT) model. Two generating models are used to simulate dichotomous responses to a 17-item test: the unidimensional and compensatory two-dimensional (C2D) models. For C2D data, seven items are modeled to load on the first and second factors, θ1 and θ2 , with the remaining 10 items modeled unidimensionally emulating a mathematics test with seven items requiring an additional reading ability dimension. For both types of generated data, the multidimensionality of item responses is investigated using HGLM and MIRT. Comparison of HGLM and MIRT's results are possible through a transformation of items' difficulty estimates into probabilities of a correct response for a hypothetical examinee at the mean on θ and θ2 . HGLM and MIRT performed similarly. The benefits of HGLM for item dimensionality analyses are discussed. 相似文献
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Allan S. Cohen Seock-Ho Kim Michael J. Subkoviak 《Journal of Educational Measurement》1991,28(1):49-59
Detection of differential item functioning (DIF) on items intentionally constructed to favor one group over another was investigated on item parameter estimates obtained from two item response theory-based computer programs, LOGIST and BILOG. Signed- and unsigned-area measures based on joint maximum likelihood estimation, marginal maximum likelihood estimation, and two marginal maximum a posteriori estimation procedures were compared with each other to determine whether detection of DIF could be improved using prior distributions. Results indicated that item parameter estimates obtained using either prior condition were less deviant than when priors were not used. Differences in detection of DIF appeared to be related to item parameter estimation condition and to some extent to sample size. 相似文献
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根据特征多项式,实数域上亏损矩阵的广义特征矩阵可用固定线性方程组求,但这个固定线性方程组的未知量个数多于方程个数,从广义若当链中选取部分等式补充到线性方程组,可使广义特征矩阵唯一确定。 相似文献
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时非齐次等式约束线性回归模型回归系数提出广义条件岭估计.证明了在一定的条件下,在均方误差矩阵、均方误差及广义均方误差意义下,广义条件岭估计都优于约束最小二乘估计和狭义条件岭估计. 相似文献
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把高等代数中线性空间的直和分解定理推广到一般情形.对于n维线性空间V上线性变换A的任一个化零多项式f（x）,若f（x）为若干个两两互素的多项式的乘积,则线性空间V可以相应地分解成有限个A的不变子空间的直和.一些应用实例被给出. 相似文献
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Randall D. Penfield 《Journal of Educational Measurement》2007,44(3):187-210
Many statistics used in the assessment of differential item functioning (DIF) in polytomous items yield a single item-level index of measurement invariance that collapses information across all response options of the polytomous item. Utilizing a single item-level index of DIF can, however, be misleading if the magnitude or direction of the DIF changes across the steps underlying the polytomous response process. A more comprehensive approach to examining measurement invariance in polytomous item formats is to examine invariance at the level of each step of the polytomous item, a framework described in this article as differential step functioning (DSF). This article proposes a nonparametric DSF estimator that is based on the Mantel-Haenszel common odds ratio estimator ( Mantel & Haenszel, 1959 ), which is frequently implemented in the detection of DIF in dichotomous items. A simulation study demonstrated that when the level of DSF varied in magnitude or sign across the steps underlying the polytomous response options, the DSF-based approach typically provided a more powerful and accurate test of measurement invariance than did corresponding item-level DIF estimators. 相似文献
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在非自然联系情形下讨论了广义线性模型拟似然方程的解βn在λ—n→∞和其他一些正则性条件下证明了解的弱相合性,并得到其收敛于真值β0的速度为Op(λ—n-1/2),其中λ—n(λ—n)为方阵Sn=iΣ=n1XiX'1的最小(最大)特征值. 相似文献
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GUO Xing-ming Shaghi Instihae of Applied Mathematics Mechanics Shanghai University Shanghai China 《上海大学学报(英文版)》2000,(Z1)
1 IntroductionClassical thermodynamics with the Parabolic-typeFourier heat conduction equation predictS that if amaterial conducting heat is subjected tO a thermaldissonance, the effectS of distalance will be feltinstancously at distances infndtely far from its source. Inother words, thermal signals Propagate at infinite speed.This Prediction is ~listic born a physical point ofview (see Ref.[l]). TO overcome such ~asonablenessand avoid the above situations, The new theory is setusually in … 相似文献