Evaluation of Maximal Reliability for Unidimensional Measuring Instruments With Correlated Errors

A latent variable modeling method for studying maximal reliability of unidimensional multicomponent measuring instruments with correlated errors is outlined. In the presence of correlation between 2 residual terms, the procedure allows one to point and interval estimate the reliability of the linear combination of the scale components that possesses the highest possible reliability coefficient. The approach is readily applicable with popular latent variable modeling software and also provides an alternative scoring rule to the widely used overall sum score for homogeneous psychometric scales. The discussed method is illustrated with a numerical example.     

Improved Estimation of Maximal Reliability for Unidimensional Multicomponent Measuring Instruments in Repeated Measure Studies

In repeated measure studies with unidimensional scales, measurement invariance, and specificity stability over time, the specificity variance in each instrument component can be identified. This article describes for that setting an improved point and interval estimation procedure for the maximal reliability coefficient associated with a given set of homogeneous measures. The method is developed within the framework of latent variable modeling and can also be readily used in longitudinal studies for improved point and interval estimation of individual measure reliability and scale reliability at each assessment occasion. The procedure is based on empirically testable conditions and is illustrated with an example.     

Maximal Criterion Validity and Scale Criterion Validity: A Latent Variable Modeling Approach for Examining Their Difference

This article studies the difference between the criterion validity coefficient of the widely used overall scale score for a unidimensional multicomponent measuring instrument and the maximal criterion validity coefficient that is achievable with a linear combination of its components. A necessary and sufficient condition of their identity is presented in the case of measurement errors being uncorrelated among themselves and with a used criterion. An upper bound of the difference in these validity coefficients is provided, indicating that it cannot exceed the discrepancy between the maximal reliability and composite reliability indexes. A readily applicable latent variable modeling procedure is discussed that can be used for point and interval estimation of the difference between the maximal and scale criterion validity coefficients. The outlined method is illustrated with a numerical example.     

Evaluation of Validity and Reliability for Hierarchical Scales Using Latent Variable Modeling

A latent variable modeling method is outlined, which accomplishes estimation of criterion validity and reliability for a multicomponent measuring instrument with hierarchical structure. The approach provides point and interval estimates for the scale criterion validity and reliability coefficients, and can also be used for testing composite or simple hypotheses about these coefficients. The proposed method is illustrated with a numerical example.     

机械零部件的可靠性设计分析

可靠性设计已广泛应用于机械零件设计.分析了机械零部件传统设计方法与可靠性设计方法在设计思想、设计原理上的区别,介绍了机械零件强度设计的应力-强度干涉理论,讨论了机械零件强度可靠度计算的一般表达式,并给出了机械零件可靠度设计的工程实例分析.通过实例设计结果的分析比较,说明可靠性设计的可行性与实用性.     

Strong Consistency of Reliability Estimators for Multiple-Component Measuring Instruments

It is shown that the maximum likelihood estimator of the widely used omega coefficient for reliability of multicomponent measuring instruments converges almost surely to the population reliability coefficient for normal congeneric measures with uncorrelated errors as sample size increases indefinitely. This strong consistency implies convergence in probability (consistency) as well as in distribution for the omega estimator. Strong consistency is also demonstrated for the maximal reliability estimator associated with the optimal linear combination of the instrument components. The findings of this note add (i) to the recommendation to use in the general normality case the omega estimator in empirical research, (ii) to the critical literature on the popular coefficient alpha then, and (iii) to the literature on the properties of the optimal linear combination of observed measures and the maximal reliability estimator.     

How Days Between Tests Impacts Alternate Forms Reliability in Computerized Adaptive Tests

An essential question when computing test–retest and alternate forms reliability coefficients is how many days there should be between tests. This article uses data from reading and math computerized adaptive tests to explore how the number of days between tests impacts alternate forms reliability coefficients. Results suggest that the highest alternate forms reliability coefficients were obtained when the second test was administered at least 2 to 3 weeks after the first test. Even though reliability coefficients after this amount of time were often similar, results suggested a potential tradeoff in waiting longer to retest as student ability tended to grow with time. These findings indicate that if keeping student ability similar is a concern that the best time to retest is shortly after 3 weeks have passed since the first test. Additional analyses suggested that alternate forms reliability coefficients were lower when tests were shorter and that narrowing the first test ability distribution of examinees also impacted estimates. Results did not appear to be largely impacted by differences in first test average ability, student demographics, or whether the student took the test under standard or extended time. It is suggested that for math and reading tests, like the ones analyzed in this article, the optimal retest interval would be shortly after 3 weeks have passed since the first test.     

Test Reliability at the Individual Level

Reliability has a long history as one of the key psychometric properties of a test. However, a given test might not measure people equally reliably. Test scores from some individuals might have considerably greater error than others. This study proposed two approaches using intraindividual variation to estimate test reliability for each person. A simulation study suggested that the parallel tests approach and the structural equation modeling approach recovered the simulated reliability coefficients. Then in an empirical study, where 45 females were measured daily on the Positive and Negative Affect Schedule (PANAS) for 45 consecutive days, separate estimates of reliability were generated for each person. Results showed that reliability estimates of the PANAS varied substantially from person to person. The methods provided in this article apply to tests measuring changeable attributes and require repeated measures across time on each individual. This article also provides a set of parallel forms of PANAS.     

机械可靠性的灵敏度研究

基于FORMS研究了机械可靠性的灵敏度。首先是建立极限状态方程,应用一次二阶迭代法求出数值,得到可靠性,σxiP 点坐标。其次是计算安全指标β,最后是β对设计参数求偏导数并代入P 点坐标X^i,μxi的灵敏度。给出了多种失效模式可靠性的灵敏度计算方法。算例表明可靠性对设计参数的灵敏度相差很大。灵敏度大小可作为再设计时修改设计参数的依据。可靠性对某一设计参数的敏感性较大,设计师在设计该参数时应给出合理的公差。需要机械加工时,应采用精加工方法,确保该设计参数精确。可靠性对某一设计参数的敏感性很小,计算可靠度时,该设计参数可以当作常数来处理,机械加工时可以采用粗加工方法。不进行灵敏度分析的机械可靠性设计是盲目的。     

多种测量信度观与自学考试信度分析

信度是衡量测量结果稳定性与可靠性的重要指标,反映了测量过程中对误差控制能力的大小。信度分析是自学考试试题评价的重要内容,包括测量分数信度分析与及格线决策信度分析。本文简要介绍了CTT信度观、GT信度观及IRT信度观的理论内容与信度分析方法,并对三种测量信度观进行比较。本文提出,自学考试的信度分析工作应结合具体课程的考试特点、试卷结构、考试作答数据类型等因素,同时考虑CTT、GT、IRT三种信度观的优势及信度估计方法的应用条件,根据具体研究目的选择最恰当的或综合运用不同的信度分析方法。     

Reliability as Argument

Reliability consists of both important social and scientific values and methods for evidencing those values, though in practice methods are often conflated with the values. With the two distinctly understood, a reliability argument can be made that articulates the particular reliability values most relevant to the particular measurement situation and then the most appropriate evidence and theory to support an argument for the presence of that value. The steps in making a reliability argument are explained and an extended example is given. The article is intended to provoke discussion, debate, and the development of additional reliability methodologies.     

Structural Reliability of Broadside of a Bulk Carrier

The ultimate bending moment and maximal shear stress of a bulk carrier with two structural forms （single hull and double hull/ are calculated separately by using the combined moment which is determined by stochastic process. Then the assessment of reliability is carried out. The results indicate that by introducing the double-hull structure, the shear stress of side can be decreased to half of that of the primary structure（ 50.7% i. but the effect on longitudinal strength is not obvious. Finally, the effects of different double-side skin widths on ultimate bending moment and the maximal shear stress are investigated, followed by proposals of the selection of the double-side skin width.     

受变载荷螺栓组联接的可靠性优化设计

承受轴向受变载荷螺栓组联接，是螺栓联接中最重要的一种形式，其设计合理与否直接影响到机械产品的成本、寿命与效益等。本文运用可靠性理论与最优化设计技术，提出了承受轴向受变载荷螺栓组联接的可靠性优化设计方法。文中以压力容器的密封螺栓组为例，讨论了可靠性优化设计数学模型的建立方法。并给出了设计实例。     

Evaluation of Reliability Coefficients for Two-Level Models via Latent Variable Analysis

A latent variable analysis procedure for evaluation of reliability coefficients for 2-level models is outlined. The method provides point and interval estimates of group means' reliability, overall reliability of means, and conditional reliability. In addition, the approach can be used to test simple hypotheses about these parameters. The procedure is applicable with unconditional models as well as with conditional models including higher level explanatory variables. The proposed method is illustrated with an empirical example.     

MATLAB在结构可靠度分析中的应用

以某砌石重力坝为例,利用结构可靠度计算方法中的JC法和Monte-Carlo法进行可靠度分析,建立结构功能函数,利用MATLAB数学软件分别对JC法和Monte-Carlo法进行编程计算,得到砌石重力坝的失效概率与可靠度指标.运行结果表明运用MATLAB编程计算精度较高,运行速度较快.     

900t提梁机液压卷扬系统的可靠性预测

可靠性建模后的可靠性预测是进行可靠性设计的重要手段。通过将该手段应用到900t提梁机液压卷扬控制系统的设计阶段,从而使系统得到不断地改进,对于提高系统本身的可靠性具有重要的意义。     

Evaluation of Dimensionality in the Assessment of Internal Consistency Reliability: Coefficient Alpha and Omega Coefficients

In the lead article, Davenport, Davison, Liou, & Love demonstrate the relationship among homogeneity, internal consistency, and coefficient alpha, and also distinguish among them. These distinctions are important because too often coefficient alpha—a reliability coefficient—is interpreted as an index of homogeneity or internal consistency. We argue that factor analysis should be conducted before calculating internal consistency estimates of reliability. If factor analysis indicates the assumptions underlying coefficient alpha are met, then it can be reported as a reliability coefficient. However, to the extent that items are multidimensional, alternative internal consistency reliability coefficients should be computed based on the parameter estimates of the factor model. Assuming a bifactor model evidenced good fit, and the measure was designed to assess a single construct, omega hierarchical—the proportion of variance of the total scores due to the general factor—should be presented. Omega—the proportion of variance of the total scores due to all factors—also should be reported in that it represents a more traditional view of reliability, although it is computed within a factor analytic framework. By presenting both these coefficients and potentially other omega coefficients, the reliability results are less likely to be misinterpreted.     

复杂系统可靠性的模拟算法研究

本文对复杂系统的可靠性进行模拟研究,给出了系统的可靠性、可靠寿命以及可靠性置信下界等可靠性指标的模拟计算公式.计算方法简单实用,是复杂系统可靠性评定的一种有效方法.     

大学生归因方式问卷的编制及信度、效度研究

问卷由正性学业成就、正性人际关系、负性学业成绩、负性人际关系四个分问卷组成。每个分问卷包括若干个条目,共16个条目(正性事件、负性事件各8条)。各个分问卷的信度系数(Cronbach,s a)在0.533-0.744之间,全问卷的分半信度为0.549。运用主成分分析法和效标效度法判断问卷的效度。研究结果表明,问卷具有较为理想的信度和效度,可作为测量、评估大学生归因方式的工具。     

马基雅维利主义人格量表的信、效度分析

为考察马基雅维利主义人格量表(MPS)在大学生群体中的适用性,以481名武汉市大学生为被试,对 MPS 进行因素分析和效、信度检验,结果显示:(1)项目分析后保留16个项目,探索性因素分析抽取4个因素,各因子及项目归属与原问卷一致,4个因子可解释总变异的52.064%.(2)验证性因素分析显示4因素模型拟合良好;MPS 总分与各因子和人格特质、操纵策略相关显著.(3)内部一致性信度为0.727-0.831,重测信度为0.715-0.837.据此认为:MPS 中文版信、效度良好