Decompositions and biplots in three-way correspondence analysis

In this paper correspondence analysis for three-way contingency tables is presented using three-way generalisations of the singular value decomposition. It is shown that in combination with Lancaster's (1951) additive decomposition of interactions in three-way tables, a detailed analysis is possible of the deviations from independence. Finally, biplots are shown to produce powerful graphical representations of the results from three-way correspondence analyses. An example from child development is used to illustrate the theoretical developments.     

Tests for stability in linear structural equation systems

Interpretations regarding the effects of exogenous and endogenous variables on endogenous variables in linear structural equation systems depend upon the convergence of a matrix power series. Convergence depends upon the eigenvalues of the structural coefficient matrix. The test for convergence developed by Jöreskog and Sörbom is shown to be only sufficient, not necessary and sufficient.     

Precipitation in a Cu–4Ti–2Be alloy

It is known that the binary Cu–2?wt.% Be alloy can be strengthened by ageing its supersaturated solution at 523?K. The increase in the strength arising from ageing is because of the formation of GP zones. The same level of strength is achieved by ageing the supersaturated solid solution of a dilute binary Cu–4?wt.% Ti alloy at 723?K. In contrast to Cu–2?wt.% Be alloy, the increase in strength in this alloy occurs on account of spinodal decomposition of the as-quenched microstructure through the mechanism of clustering and ordering. In the present study, decomposition of a supersaturated solid solution of the ternary Cu–4?wt.% Ti–2?wt.% Be alloy was studied. Whereas ageing of this alloy at 523?K resulted in the formation of GP zones like in a Cu–2?wt.% Be alloy, ageing at 723?K resulted in a spinodally decomposed microstructure as in a Cu–4?wt.% Ti alloy. The decomposition of the ternary alloy at the two temperatures by two different mechanisms indicates that Be and Ti in solution in Cu act, more or less, independently of each other during ageing.     

Electropulsing-induced strengthening of steel at high temperature

Electropulsing usually promotes a metastable phase to evolve towards its equilibrium state. This work reports an alternative case, where electropulsing promotes the decomposition of the stable δ-phase in duplex stainless steel at high temperature. This decomposition enables both the γ-phase and the σ-phase in the steel to survive and hence to strengthen it at high temperature. The hardness of the quenched sample with electropulsing treatment is 49.4% higher than that without electropulsing treatment. A fundamental understanding of the observation is developed.     

Visual experience is not necessary for efficient survey spatial cognition: Evidence from blindness

This study investigated whether the lack of visual experience affects the ability to create spatial inferential representations of the survey type. We compared the performance of persons with congenital blindness and that of blindfolded sighted persons on four survey representation-based tasks (Experiment 1). Results showed that persons with blindness performed better than blindfolded sighted controls. We repeated the same tests introducing a third group of persons with late blindness (Experiment 2). This last group performed better than blindfolded sighted participants, whereas differences between participants with late and congenital blindness were nonsignificant. The present findings are compatible with results of other studies, which found that when visual perception is lacking, skill in gathering environmental spatial information provided by nonvisual modalities may contribute to a proper spatial encoding. It is concluded that, although it cannot be asserted that total lack of visual experience incurs no cost, our findings are further evidence that visual experience is not a necessary condition for the development of spatial inferential complex representations.     

Decomposition,Interdependence and Precision in Multiattribute Utility Measurements

Traditionally, parameters of multiattribute utility models, representing a decision maker's preference judgements, are treated deterministically. This may be unrealistic, because assessment of such parameters is potentially fraught with imprecisions and errors. We thus treat such parameters as stochastic and investigate how their associated imprecision/errors are propagated in an additive multiattribute utility function in terms of the aggregate variance. Both a no information and a rank order case regarding the attribute weights are considered, assuming a uniform distribution over the feasible region of attribute weights constrained by the respective information assumption. In general, as the number of attributes increases, the variance of the aggregate utility in both cases decreases and approaches the same limit, which depends only on the variances as well as the correlations among the single-attribute utilities. However, the marginal change in aggregate utility variance decreases rather rapidly and hence decomposition as a variance reduction mechanism is generally useful but becomes relatively ineffective if the number of attributes exceed about 10. Moreover, it was found that utilities which are positively correlated increase the aggregate utility variance, hence every effort should be made to avoid positive correlations between the single-attribute utilities. We also provide guidelines for determining under what condition and to what extent a decision maker should decompose to obtain an aggregate utility variance that is smaller than that of holistic assessments. Extensions of the current model and empirical research to support some of our behavioural assumptions are discussed. © 1997 John Wiley & Sons, Ltd.     

Taxicab Correspondence Analysis

Taxicab correspondence analysis is based on the taxicab singular value decomposition of a contingency table, and it shares some similar properties with correspondence analysis. It is more robust than the ordinary correspondence analysis, because it gives uniform weights to all the points. The visual map constructed by taxicab correspondence analysis has a larger sweep and clearer perspective than the map obtained by correspondence analysis. Two examples are provided. This research was financed by the Natural Sciences and Engineering Research Council of Canada. The author thanks Serge Vienneau for his help regarding the graphical displays, and also thanks the editor, associate editor, and two reviewers for their constructive comments.     

学习因素对语义信息加工性质的影响

本研究通过两个行为实验,采用句子核证作业,将SAD技术和范畴学习范式有机地结合起来,对语义信息加工进程以及学习因素在其中的作用进行了考察。实验一研究了熟悉性对语义信息加工的影响。结果表明,高熟悉句的部分信息积累具有离散的趋势;低熟悉句的部分信息积累是连续性的。实验二采用范畴学习。并结合SAD技术的句子核证作业．考察了在学习过程中语义加工性质的变化。结果发现：过度学习比初始学习有更多的部分信息积累,并随信号间隔的延长而逐渐增加;过度学习表现出部分信息积累的离散性变化;初始学习则表现出连续累积的趋势。说明学习确实造成了连续性加工向离散性质的过渡。     

Sublexical and morphological information in speech processing

Three experiments investigated the impact of syllabic boundary information and of morphological structure on performance in a sequence-monitoring task. In sequence monitoring, participants detect pre-specified sequences of phonemes in spoken carrier words. Sequences corresponded to the first syllable of the carrier word, to its first morpheme, or simultaneously to both. The data from Experiments 1 and 2, using different variants of the monitoring task, showed a strong impact of syllable boundary cues on monitoring latencies. An effect of morphological match between targets and carrier words was also evident. Experiment 3, in which parts of the spoken carrier words were cross-spliced, revealed that syllabic boundary information takes precedence over morphological information. The results are in line with an early process of speech processing, in which syllabic cues are used to aid lexical access. The morphological effect is better understood as a later, probably lexical, contribution of morphological decomposition to monitoring performance.     

Phase-transformation-induced hardening in Zn–22Al alloys

A phase-transformation-induced hardening effect is reported in Zn–22Al (Al: 22?wt.%) alloys. The Zn–22Al specimens were held at 300?°C for 10?h and then quenched in water. A hardening effect took place in subsequent artificial aging at 100–200?°C, which was accompanied by a phase decomposition of a soft α ₂ phase and a grain coarsening. The phase-transformation-induced hardening affects the hardness more than the grain-coarsening-induced softening, which leads to the age-hardening phenomenon.