bluuebunny/crossref_metadata_2025 huggingface dataset:
One‐Pot Method for Stereoselective Cyclopropanation of Electron‐Deficient Olefins with Methyl Bromoacetate and Phenacyl Bromide in the Presence of Triphenylarsine.
Authors: Ren Zhongjiao , Cao Weiguo , Ding Weiyu , Wang Yu
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
The First Buckybowl Aryne. Corannulyne: A Nonplanar Benzyne.
Authors: Sygula Andrzej , Sygula Renata , Rabideau Peter W.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Microwave‐Assisted Addition of Pyrroles to Electron‐Deficient Olefins: A Rapid Entry to C‐Alkyl Pyrroles.
Authors: Zhan Zhuang‐Ping , Yang Wen‐Zhen , Yang Rui‐Feng
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Preparation of RCM Substrates for Azepinoindole Synthesis: Reductive Amination versus Tetrahydro‐γ‐carboline Formation.
Authors: Bennasar M.‐Lluisa , Zulaica Ester , Alonso Sandra
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Ring‐Opening Reactions of Cyclopropanes. Part 8. Nitrosation of Donor—Acceptor Cyclopropanes.
Authors: Cermola Flavio , Di Gioia Lucrezia , Graziano Maria Liliana , Iesce Maria Rosaria
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Synthesis and Caspase‐3 Inhibitory Activity of 8‐Sulfonyl‐1,3‐dioxo‐2,3‐dihydro‐1H‐pyrrolo[3,4‐c]quinolines.
Authors: Kravchenko Dmitri V. , Kysil Volodymyr M. , Tkachenko Sergey E. , Maliarchouk Sergey , Okun Ilya M. , Ivachtchenko Alexandre V.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Multicomponent Condensation of Aliphatic Amines with Formaldehyde and Hydrogen Sulfide.
Authors: Khafizova S. R. , Akhmetova V. R. , Korzhova L. F. , Tyumkina T. V. , Nadyrgulova G. R. , Kunakova R. V. , Kruglov E. A. , Dzhemilev U. M.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Synthesis of 9‐Thia‐3,7‐diazabicyclo[3.3.1]nonane 9,9‐Dioxides.
Authors: Vlasova L. I. , Baibulatova N. Z. , Latypova D. R. , Yunusov M. S. , Dokichev V. A. , Tomilov Yu. V.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Phosphorylation of 1,4‐Bis(hydroxymethyl)benzene.
Authors: Rasadkina E. N. , Slitikov P. V. , Stash A. I. , Nifant'ev E. E.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Total Synthesis of (.+‐.)‐Ceratopicanol: Application of Pd‐Catalyzed Enediyne Cycloreduction.
Authors: Oh Chang Ho , Rhim Chul Yun , Kim Mira , Park Dai In , Gupta Aruna Kumar
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Chemical Optimization of Artificial Metalloenzymes Based on the Biotin‐Avidin Technology: (S)‐Selective and Solvent‐Tolerant Hydrogenation Catalysts via the Introduction of Chiral Amino Acid Spacers.
Authors: Skander Myriem , Malan Christophe , Ivanova Anita , Ward Thomas R.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Synthesis of Ring‐A‐Substituted Tryptophan by a Palladium‐Catalyzed Heteroannulation Reaction.
Authors: Jia Yanxing , Zhu Jieping
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Four New Phenones (I)‐(III) from the Cortexes of Polygala tenuifolia.
Authors: Jiang Yong , Tu Pengfei
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Two New Dimeric Coumarins Isolated from Murraya exotica.
Authors: Ju‐ichi Motoharu , et al. et al.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Biflavone Glucosides from Ginkgo biloba Yellow Leaves.
Authors: Hyun Sook Kyung , Kang Sam Sik , Son Kun Ho , Chung Hae Young , Choi Jae Sue
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Structure of Nystatin A2.
Authors: Pawlak J. , Tabin P. , Sowinski P. , Borowski E.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
New Plastoquinones Isolated from the Brown Alga, Sargassum micracanthum.
Authors: Mori Jun , Iwashima Makoto , Wakasugi Hiroko , Saito Haruo , Matsunaga Takayuki , Ogasawara Masaru , Takahashi Satoshi , Suzuki Hideyo , Hayashi Toshimitsu
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
FR258900, a Novel Glycogen Phosphorylase Inhibitor Isolated from Fungus No.138354. Part 1. Taxonomy, Fermentation, Isolation and Biological Activities.
Authors: Furukawa Shigetada , Tsurumi Yasuhisa , Murakami Kana , Nakanishi Tomoko , Ohsumi Keisuke , Hashimoto Michizane , Nishikawa Motoaki , Takase Shigehiro , Nakayama Osamu , Hino Motohiro
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Synthesis and Properties of Isocannabinoid and Cholesterol Derivatized Rhamnosurfactants: Application to Liposomal Targeting of Keratinocytes and Skin.
Authors: Barragan‐Montero Veronique , Winum Jean‐Yves , Moles Jean‐Pierre , Juan Emmanuelle , Clavel Caroline , Montero Jean‐Louis
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Preparation of 3‐Spirocyclic Indolin‐2‐ones as Ligands for the ORL‐1 Receptor.
Authors: Bignan Gilles C. , Battista Kathleen , Connolly Peter J. , Orsini Michael J. , Liu Jingchun , Middleton Steven A. , Reitz Allen B.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Collective Spin and Charge Excitations in (Sr,La)14‐xCaxCu24O41 Quantum Spin Ladders
Authors: Gozar A. , Blumberg G.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Selectfluor (F‐TEDA‐BF4) as a Versatile Mediator or Catalyst in Organic Chemistry
Authors: Stavber Stojan , Zupan Marko
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Stephacidin B, the Avrainvillamide Dimer: A Formidable Synthetic Challenge
Authors: Escolano Carmen
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Selective Synthetic Methods Using Vanadium‐Mediated Redox Reactions
Authors: Hirao Toshikazu
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Polycarnitine: A New Biomaterial
Authors: Kamm B. , Kamm M. , Kiener A. , Meyer H.‐P.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Responses of large volcanic eruptions in the instrumental and documentary climatic data over Central Europe
Authors: Písek Jan , Brázdil Rudolf
Published: January 2006

Responses of large volcanic eruptions in selected long temperature series from Austria, the Czech Republic and Germany as well as in three global radiation series in Central Europe are studied. In the example of seven large tropical eruptions (Krakatau 1883; Pelée, Soufriére and Santa María 1902; Agung, 1963; El Chichón, 1982; Mt Pinatubo, 1991) it has been demonstrated that volcanic signal in regional series is not so strongly expressed as in the hemispheric scale owing to different local effects and circulation patterns. This is also valid in the case of two further discussed eruptions of Tambora (1815) and Katmai (1912). The responses of eruptions in areas closer to Central Europe such as Iceland or Italy are more important. In nine analysed cases with VEI = 4–5 with a single exception of the Hekla eruption (1917), cold seasons were observed to follow the eruption. Responses to the Lakagígar eruption (1783) of Iceland with important impacts are also discussed in detail. Moreover, correlation between temperatures (annual and winter half‐year series) and NAOI is prevailingly smaller for the period following eruptions than in the period preceding eruptions. The importance of documentary evidence as a valuable source of the information about the impacts of volcanic eruptions is demonstrated. Copyright © 2006 Royal Meteorological Society.
Morphological and mechanical properties of carbon nanotube/polymer composites via melt compounding
Authors: Dondero William E. , Gorga Russell E.
Published: January 2006

The mechanical properties and morphology of multiwall carbon nanotube (MWNT)/polypropylene (PP) nanocomposites were studied as a function of nanotube orientation and concentration. Through melt mixing followed by melt drawing, using a twin screw mini‐extruder with a specially designed winding apparatus, the dispersion and orientation of MWNTs was optimized in PP. Tensile tests showed a 32% increase in toughness for a 0.25 wt % MWNT in PP (over pure PP). Moreover, modulus increased by 138% with 0.25 wt % MWNTs. Transmission electron microscopy and scanning electron microscopy demonstrated qualitative nanotube dispersion and orientation. Wide angle X‐ray diffraction was used to study crystal morphology and orientation by calculating the Herman's orientation factor for the composites as function of nanotube loading and orientation. The addition of nanotubes to oriented samples causes the crystalline morphology to shift from α and mesophase to only α phase. Furthermore, the addition of nanotubes (without orientation) was found to cause isotropization of the PP crystal, and drawing was shown to improve crystal orientation through the orientation factor. In addition, differential scanning caloriometry qualitatively revealed little change in overall crystallinity. In conclusion, this work has shown that melt mixing coupled with melt drawing has yielded MWNT/PP composites with a unique combination of strength and toughness suitable for advanced fiber applications, such as smart fibers and high‐performance fabrics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 864–878, 2006
Words derived from the noun peptide
Authors: Jones John H
Published: January 2006

Modifications of the noun peptide are explored and clarified; a few are condemned. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
A Strategy for the Identification of Canonical and Non‐canonical MHC I‐binding Epitopes Using an ANN‐based Epitope Prediction Algorithm
Authors: Filter Matthias , Eichler‐Mertens Mathias , Bredenbeck Anne , Losch Florian O. , Sharav Tumenjargal , Givehchi Alireza , Walden Peter , Wrede Paul
Published: January 2006

Small peptides bound by Major Histocompatibility Complex (MHC) class I molecules and recognized in this context by the T‐cell receptor of CD8+ T cells are known as T‐cell epitopes and are of extraordinary importance for the development of new vaccines against cancer and viral infections. Several algorithms predicting a peptide's binding capability to a given MHC class I molecule are currently available and have been successfully applied in the identification of new T‐cell epitopes within proteins. Most of these newly identified epitopes obey to the empirically determined anchor residue patterns that are specific for the different MHC I alleles. However, in recent studies an increasing number of weakly binding T‐cell epitopes could be identified that do not fit to these canonical amino acid patterns. Therefore there is a need for new prediction algorithms improving the prediction accuracy for weakly binding epitopes that are biologically relevant as they are presented by, e.g. antigen presenting cells.
Some Comparisons of the Multiple-Factor and the Bi-Factor Methods of
Analysis
Authors: Swineford Frances
Published: January 2006

Bi-factor and multiple-factor analyses of the same data are compared in
two respects. First, two criteria are suggested for determining when the
factorization is adequate. This problem being more acute for the centroid
method than for the bi-factor method, the latter is used primarily for
comparison only. It is shown also that the omission from the simple
structure of entries smaller than .10 yields a pattern which is a poorer fit
to the original correlations than is the bi-factor pattern. Second, the
second-order general factor obtained from the intercorrelations of the
primaries is found to be highly correlated with the general factor of the
bi-factor pattern.
The Additive Constant Problem in Multidimensional Scaling
Authors: Messick Samuel J. , Abelson Robert P.
Published: January 2006

The problem of choosing the correct additive constant to convert relative interstimulus distances to absolute interstimulus distances in multidimensional scaling is investigated. An artificial numerical example is constructed, and various trial values of the constant are inserted to demonstrate the effect on the multidimensional map of making a variety of incorrect choices. Finally, a general solution to the problem, suggested by Dr. Ledyard R Tucker, is presented; each of the computational steps in this solution is set down for easy reference.
The Regression of Gains Upon Initial Scores
Authors: Garside R. F.
Published: January 2006

A method of estimating the regression of gains upon initial scores is suggested and compared with two other methods which have been used in recent investigations.
Proportional Profiles and Latent Structure
Authors: Gibson W. A.
Published: January 2006

The identity of problem and solution in Lazarsfeld's latent structure analysis and Cattell's proportional profiles is pointed out. Anderson's latent structure solution is adapted to proportional profiles to yield a possible solution for the communality and rotational problems in factor analysis. A numerical example of the latter is provided.
Testing Message Diffusion in Harmonic Logistic Curves
Authors: Dodd Stuart Carter
Published: January 2006

The growth of a population of knowers of a message was studied to test a human interactance hypothesis. The conditions investigated involved people interacting in time, with the population pairing off randomly (i.e., determined by many, small, different influences) and transferring an attribute (i.e., an all-or-none act) at either a steady rate or a waning rate, subsequent to the originating stimulus. The mathematical expressions for these pre-conditions were the differential equations for the linear logistic for steady acting and the harmonic logistic for waning acting. Variant forms of these curves were developed. Two exploratory experiments, or pretests, comprised launching a coffee slogan in a town and imitating a badge wearer in a boys' camp. Since the activity rate waned harmonically in both cases, the harmonic logistic fit best in both the town and the camp as expected by the hypothesis.
A Method for Obtaining an Ordered Metric Scale
Authors: Siegel Sidney
Published: January 2006

A method is presented for collecting data which will yield a scale on which the entities are ranked in preference (ordinality), the distances between the entities on the scale are ranked (ordered metric), and all combinations of the distances are ranked (higher-ordered metric). The sources drawn upon are von Neumann and Morgenstern (9), and lattice theory. An empirical example is given in which a higher-ordered metric scale is derived.
Development of a Method for Increasing the Utility of Multiple Correlations by Considering both Testing Time and Test Validity
Authors: Long W. F. , Burr Irving W.
Published: January 2006

A modification of the Wherry-Doolittle test selection method is presented by which tests are included in a multiple correlation (obtained for a given battery of tests) in the sequence in which the rate of return in validity per unit of testing time is greatest, rather than in the order of the size of their contribution to the multiple correlation. It is proposed that the modified method can be utilized profitably when there are economic or practical limits on the time available for test administration.
Confirmation and Clarification of Primary Personality Factors
Authors: Cattell Raymond B.
Published: January 2006

In connection with a study bridging rating, questionnaire, and objective test factors, confirmation was sought with respect to the twelve personality factors previously found for young adult men. Variables were chosen to clarify and discriminate the nature of related factors. Ratings of and by 373 students were obtained, and the present study describes the separate factorization for the 133 men among them. Factorization yielded eleven factors, of which, on “blind” rotation for simple structure, 9 or 10 proved to be identical with those of the previous study. A new factor M is described.
Correlation in a Singly Truncated Bivariate Normal Distribution
Authors: Aitkin M. A.
Published: January 2006

The correlation in a singly truncated binormal distribution is obtained in terms of Mills' ratio using the Mehler identity. A table of the correlation in the underlying distribution as a function of the correlation in the truncated distribution is presented, together with a diagram summarizing this relationship.
The Distribution of Chance Congruence Coefficients from Simulated Data
Authors: Korth Bruce , Tucker Ledyard R
Published: January 2006

All attempts to study the stability of factors depend on having some useful statistic that measures the degree of similarity between factors. This study attempts to provide some normative data about the distribution of one measure of similarity, the congruence coefficient, through a Monte Carlo technique. The matching of “chance” factor patterns was done by the method of Tucker. Statistical tests of the results, based on similarities of the method to canonical and multiple correlation, seemed satisfactory. The tabled results can be used as guides to the significance of congruence coefficients for some cases. The consistencies of the data indicate that a functional resolution may be possible, but none was found.
Statistics as Psychometrics
Authors: Novick Melvin R.
Published: January 2006

In this paper, modern statistics is considered as a branch of psychometrics and the question of how the central problems of statistics can be resolved using psychometric methods is investigated. Theories and methods developed in the fields of test theory, scaling, and factor analysis are related to the principle problems of modern statistical theory and method. Topics surveyed include assessment of probabilities, assessment of utilities, assessment of exchangeability, preposterior analysis, adversary analysis, multiple comparisons, the selection of predictor variables, and full-rank ANOVA. Reference is made to some literature from the field of cognitive psychology to indicate some of the difficulties encountered in probability and utility assessment. Some methods for resolving these difficulties using the Computer-Assisted Data Analysis (CADA) Monitor are described, as is some recent experimental work on utility assessment.
Piecewise Method of Reciprocal Averages for Dual Scaling of Multiple-Choice Data
Authors: Nishisato Shizuhiko , Sheu Wen-Jenn
Published: January 2006

The proposed method handles the classical method of reciprocal averages (MRA) in a piecewise (item-by-item) mode, whereby one can deal with smaller matrices and attain faster convergence to a solution than the MRA. A new concept “the principle of constant proportionality” is introduced to provide an interesting interpretation for scaling multiple-choice data á la Guttman. A small example is presented for discussion of the technique.
An Alternative to the Methodology for Analysis of Covariance
Authors: Sörbom Dag
Published: January 2006

A general statistical model for simultaneous analysis of data from several groups is described. The model is primarily designed to be used for the analysis of covariance. The model can handle any number of covariates and criterion variables, and any number of treatment groups. Treatment effects may be assessed when the treatment groups are not randomized. In addition, the model allows for measurement errors in the criterion variables as well as in the covariates. A wide variety of hypotheses concerning the parameters of the model can be tested by means of a large sample likelihood ratio test. In particular, the usual assumptions of ANCOVA may be tested.
Constrained Multidimensional Scaling in N Spaces
Authors: Bloxom Bruce
Published: January 2006

A gradient method is used to obtain least squares estimates of parameters of the m-dimensional euclidean model simultaneously in N spaces, given the observation of all pairwise distances of n stimuli for each space. The procedure can estimate an additive constant as well as stimulus projections and the metric of the reference axes of the configuration in each space. Each parameter in the model can be fixed to equal some a priori value, constrained to be equal to any other parameter, or free to take on any value in the parameter space. Two applications of the procedure are described.
Three Notes on ALSCAL
Authors: Young Forrest W. , Takane Yoshio , Lewyckyj Rostyslaw
Published: January 2006

It is reported that (1) a new coordinate estimation routine is superior to that originally proposed for ALSCAL; (2) an oversight in the interval measurement level case has been found and corrected; and (3) a new initial configuration routine is superior to the original.
Orthogonal Procrustes Rotation Maximizing Congruence
Authors: Brokken Frank B.
Published: January 2006

Procedures for assessing the invariance of factors found in data sets using different subjects and the same variables are often using the least squares criterion, which appears to be too restrictive for comparing factors.

Tucker's coefficient of congruence, on the other hand, is more closely related to the human interpretation of factorial invariance than the least squares criterion. A method maximizing simultaneously the sum of coefficients of congruence between two matrices of factor loadings, using orthogonal rotation of one matrix is presented. As shown in examples, the sum of coefficients of congruence obtained using the presented rotation procedure is slightly higher than the sum of coefficients of congruence using Orthogonal Procrustes Rotation based on the least squares criterion.
Statistical Bias in Maximum Likelihood Estimators of Item Parameters
Authors: Lord Frederic M.
Published: January 2006

Asymptotic formulas are derived for the bias in the maximum likelihood estimators of the item parameters in the logistic item response model when examinee abilities are known. Numerical results are given for a typical verbal test for college admission.
Ordinal Data, Ordered Scale Points, and Order Statistics
Authors: Vijn Pieter
Published: January 2006

This paper concerns ordinal responses. An ordered Dirichlet distribution describes prior and posterior beliefs about the cumulative probabilities of response categories. Associating the response categories with intervals of a latent random variable then induces a distribution on the order statistics of that variable. The psychometrician can use the asymptotic theory of order statistics to learn how distributional assumptions about the latent variable effect inference. An example relates the skewness of a latent variable to the proportional odds and proportional hazards models of McCullagh [1980].
Simulating Multivariate Nonnormal Distributions
Authors: Vale C. David , Maurelli Vincent A.
Published: January 2006

A method for generating multivariate nonnormal distributions with specified intercorrelations and marginal means, variances, skews, and kurtoses is proposed. As an example, the method is applied to the generation of simulated scores on three psychological tests administered to a single group of individuals.
A Note on the use of Directional Statistics in Weighted Euclidean Distances Multidimensional Scaling Models
Authors: Jones Charles L.
Published: January 2006

The weighted euclidean distances model in multidimensional scaling (WMDS) represents individual differences as dimension saliences which can be interpreted as the orientations of vectors in a subject space. It has recently been suggested that the statistics of directions would be appropriate for carrying out tests of location with such data. The nature of the directional representation in WMDS is reviewed and it is argued that since dimension saliences are almost always positive, the directional representations will usually be confined to the positive orthant. Conventional statistical techniques are appropriate to angular representations of the individual differences which will yield angles in the interval (0, 90) so long as dimension saliences are nonnegative, a restriction which can be imposed. Ordinary statistical methods are also appropriate with several linear indices which can be derived from WMDS results. Directional statistics may be applied more fruitfully to vector representations of preferences.
Maximum Likelihood Estimation of Item Response Parameters when Some Responses are Omitted
Authors: Lord Frederic M.
Published: January 2006

A theoretical model is given for dealing with omitted responses. Two special cases are investigated.
Gennclus: New Models for General Nonhierarchical Clustering Analysis
Authors: Desarbo Wayne S.
Published: January 2006

A general class of nonhierarchical clustering models and associated algorithms for fitting them are presented. These (metric) clustering models generalize the Shepard-Arabie Additive Clusters model in allowing for: (1). either overlapping or nonoverlapping clusters; (2). either symmetric (one-way clustering) or nonsymmetric (two-way clustering) proximities (input data); and, (3). either symmetric or diagonal weights. The GENNCLUS algorithms utilize alternating least-squares methods combining ordinary and constrained least-squares, nonlinear constrained mathematical programming, and combinatorial optimization techniques in estimating model parameters. In addition to developing the mathematical bases of these models, a comprehensive set of Monte Carlo simulations of the different models is reported. Two applications concerning brand-switching data and celebrity-brand proximities are discussed. Finally, extensions to three-way models, nonmetric analyses, and other model specifications are provided.
Problems with Bootstrapping Pearson Correlations in Very Small Bivariate Samples
Authors: Dolker Michael , Halperin Silas , Divgi D. R.
Published: January 2006

Efron's Monte Carlo bootstrap algorithm is shown to cause degeneracies in Pearson's r for sufficiently small samples. Two ways of preventing this problem when programming the bootstrap of r are considered.
Testing the Identity of Trends under the Restriction of Monotonicity in Repeated Measures Designs
Authors: Huynh Huynh
Published: January 2006

Procedures are described for the analysis of profiles of means in repeated measures designs under order restriction for patterns of mean change. The exact likelihood ratio is derived for the case of two groups of subjects, and a computationally simple alternative to the exact likelihood ratio test is provided for designs involving more than two groups. Tables of critical values are provided for the case of simple-order alternatives.
Canonical/Redundancy Factoring Analysis
Authors: DeSarbo Wayne S.
Published: January 2006

The interrelationships between two sets of measurements made on the same subjects can be studied by canonical correlation. Originally developed by Hotelling [1936], the canonical correlation is the maximum correlation between linear functions (canonical factors) of the two sets of variables. An alternative statistic to investigate the interrelationships between two sets of variables is the redundancy measure, developed by Stewart and Love [1968]. Van Den Wollenberg [1977] has developed a method of extracting factors which maximize redundancy, as opposed to canonical correlation.

A component method is presented which maximizes user specified convex combinations of canonical correlation and the two nonsymmetric redundancy measures presented by Stewart and Love. Monte Carlo work comparing canonical correlation analysis, redundancy analysis, and various canonical/redundancy factoring analyses on the Van Den Wollenberg data is presented. An empirical example is also provided.
MSA for a Special Spearman Matrix
Authors: Meyer Edward P. , Kaiser Henry F. , Cerny Barbara A. , Green Bert F.
Published: January 2006

Kaiser's measure of sampling adequacy is applied to a special Spearman matrix and a special q-cluster generalization. The result supports the contention that the measure should be no less than .5 for data to be appropriate for factor analysis.
Some Symmetric, Invariant Measures of Multivariate Association
Authors: Cramer Elliot M. , Nicewander W. Alan
Published: January 2006

A distinction is drawn between redundancy measurement and the measurement of multivariate association for two sets of variables. Several measures of multivariate association between two sets of variables are examined. It is shown that all of these measures are generalizations of the (univariate) squared-multiple correlation; all are functions of the canonical correlations, and all are invariant under linear transformations of the original sets of variables. It is further shown that the measures can be considered to be symmetric and are strictly ordered for any two sets of observed variables. It is suggested that measures of multivariate relationship may be used to generalize the concept of test reliability to the case of vector random variables.
Exact Conditional Tests for Cross-Classifications: Approximation of Attained Significance Levels
Authors: Agresti Alan , Wackerly Dennis , Boyett James M.
Published: January 2006

A procedure is proposed for approximating attained significance levels of exact conditional tests. The procedure utilizes a sampling from the null distribution of tables having the same marginal frequencies as the observed table. Application of the approximation through a computer subroutine yields precise approximations for practically any table dimensions and sample size.
Joint-Space Analysis of “pick-any” Data: Analysis of Choices from an Unconstrained Set of Alternatives
Authors: Levine Joel H.
Published: January 2006

Social and naturally occurring choice phenomena are often of the “pick-any” type in which the number of choices made by a subject as well as the set of alternatives from which they are chosen is unconstrained. These data present a special analytical problem because the meaning of non-choice among pick-any choice data is always ambiguous: A non-chosen alternative may be either unacceptable, or acceptable but not considered, or acceptable and considered but not chosen. A model and scaling method for these data are introduced, allowing for this ambiguity of non-choice. Subjects are represented as points whose coordinates are proportional to the centroids of the points representing their choices. Alternatives are represented at points whose coordinates are proportional to the centroids of the points representing subjects who have chosen them. This centroid scaling technique estimates multidimensional joint spaces from the pick-any data.
Nonmetric Maximum Likelihood Multidimensional Scaling from Directional Rankings of Similarities
Authors: Takane Yoshio , Carroll J. Douglas
Published: January 2006

A maximum likelihood estimation procedure is developed for multidimensional scaling when (dis)similarity measures are taken by ranking procedures such as the method of conditional rank orders or the method of triadic combinations. The central feature of these procedures may be termed directionality of ranking processes. That is, rank orderings are performed in a prescribed order by successive first choices. Those data have conventionally been analyzed by Shepard-Kruskal type of nonmetric multidimensional scaling procedures. We propose, as a more appropriate alternative, a maximum likelihood method specifically designed for this type of data. A broader perspective on the present approach is given, which encompasses a wide variety of experimental methods for collecting dissimilarity data including pair comparison methods (such as the method of tetrads) and the pick-M method of similarities. An example is given to illustrate various advantages of nonmetric maximum likelihood multidimensional scaling as a statistical method. At the moment the approach is limited to the case of one-mode two-way proximity data, but could be extended in a relatively straightforward way to two-mode two-way, two-mode three-way or even three-mode three-way data, under the assumption of such models as INDSCAL or the two or three-way unfolding models.
Multivariate Stochastic Processes Compatible with “Aspect” Models of Similarity and Choice
Authors: Marley A. A. J.
Published: January 2006

Various recent works have developed “feature” or “aspect” models of similarity and preference. These models are more concerned with the fine detail of the judgment process than were prior models, but nevertheless they have not in general developed an underlying stochastic process compatible with the assumed structure. In this paper, we show that a particular class of multivariate stochastic processes, namely those associated with the Marshall-Olkin multivariate exponential distribution, generates several of these models. In particular, such stochastic processes (appropriately interpreted) yield Tversky's elimination by aspects model, Edgell and Geisler's (normal) additive random aspects model, and Shepard and Arabie's additive cluster model.
A Note on ALSCAL: The Estimation of the Additive Constant
Authors: Verhelst N. D.
Published: January 2006

A method is given for the least squares regression of a squared variable d2 on the squared variable 02, where the relation between 0 and d is linear. The problem arises in MDS-algorithms where the loss function is defined in terms of squared distances (e.g., ALSCAL). It is pointed out that the Lagrangian multiplier is a root of fourth degree polynomial.
Structural Analysis of Covariance and Correlation Matrices
Authors: Jöreskog Karl G.
Published: January 2006

A general approach to the analysis of covariance structures is considered, in which the variances and covariances or correlations of the observed variables are directly expressed in terms of the parameters of interest. The statistical problems of identification, estimation and testing of such covariance or correlation structures are discussed.

Several different types of covariance structures are considered as special cases of the general model. These include models for sets of congeneric tests, models for confirmatory and exploratory factor analysis, models for estimation of variance and covariance components, regression models with measurement errors, path analysis models, simplex and circumplex models. Many of the different types of covariance structures are illustrated by means of real data.
A Direct Approach to Individual differences Scaling using Increasingly Complex Transformations
Authors: Lingoes James C. , Borg Ingwer
Published: January 2006

A family of models for the representation and assessment of individual differences for multivariate data is embodied in a hierarchically organized and sequentially applied procedure called PINDIS. The two principal models used for directly fitting individual configurations to some common or hypothesized space are the dimensional salience and perspective models. By systematically increasing the complexity of transformations one can better determine the validities of the various models and assess the patterns and commonalities of individual differences. PINDIS sheds some new light on the interpretability and general applicability of the dimension weighting approach implemented by the commonly used INDSCAL procedure.
Extending the Temporal Range of Psychometric Prediction by Optimal Linear Filtering of Mental Test Scores
Authors: Dröler Jan
Published: January 2006

Incorporating temporal decline in predictive validity into mental testing theory is outlined. Starting from multivariate regression of criterion on repeated measurements, an analytic extension results in a weighting function for repeated measurements, replacing the beta weights. Besides optimizing, the procedure permits an evaluation of any particular prognosis setting: In cases of exponentially declining predictive validity, prognostic range can be extended if concurrent validity is nonperfect by optimal weighting (“predictive filtering”) of repeated measurements. Considerable gain in prognostic range over the traditional approach can be achieved if predictive validity declines concavely downwards.
A Rating Formulation for Ordered Response Categories
Authors: Andrich David
Published: January 2006

A rating response mechanism for ordered categories, which is related to the traditional threshold formulation but distinctively different from it, is formulated. In addition to the subject and item parameters two other sets of parameters, which can be interpreted in terms of thresholds on a latent continuum and discriminations at the thresholds, are obtained. These parameters are identified with the category coefficients and the scoring function of the Rasch model for polychotomous responses in which the latent trait is assumed uni-dimensional. In the case where the threshold discriminations are equal, the scoring of successive categories by the familiar assignment of successive integers is justified. In the case where distances between thresholds are also equal, a simple pattern of category coefficients is shown to follow.
A Series of Lower Bounds to the Reliability of a Test
Authors: ten Berge Jos. M. F. , Zegers Frits E.
Published: January 2006

Two well-known lower bounds to the reliability in classical test theory, Guttman’s λ2 and Cronbach’s coefficient alpha, are shown to be terms of an infinite series of lower bounds. All terms of this series are equal to the reliability if and only if the test is composed of items which are essentially tau-equivalent. Some practical examples, comparing the first 7 terms of the series, are offered. It appears that the second term (λ2) is generally worth-while computing as an improvement of the first term (alpha) whereas going beyond the second term is not worth the computational effort. Possibly an exception should be made for very short tests having widely spread absolute values of covariances between items. The relationship of the series and previous work on lower bound estimates for the reliability is briefly discussed.
Confidence Regions for Multidimensional Scaling Analysis
Authors: Ramsay J. O.
Published: January 2006

Techniques are developed for surrounding each of the points in a multidimensional scaling solution with a region which will contain the population point with some level of confidence. Bayesian credibility regions are also discussed. A general theorem is proven which describes the asymptotic distribution of maximum likelihood estimates subject to identifiability constraints. This theorem is applied to a number of models to display asymptotic variance-covariance matrices for coordinate estimates under different rotational constraints. A technique is described for displaying Bayesian conditional credibility regions for any sample size.
Some Approximate Tests for Repeated Measurement Designs
Authors: Huynh Huynh
Published: January 2006

Four approximate tests are considered for repeated measurement designs in which observations are multivariate normal with arbitrary covariance matrices. In these tests traditional within-subject mean square ratios are compared with critical values derived from F distributions with adjusted degrees of freedom. Two of them—the ∈ approximate and the improved general approximate (IGA) tests-behave adequately in terms of Type I error. Generally, the IGA test functions better than the ∈ approximate test, however the latter involves less computations. In regards to power, the IGA test may compete with one multivariate procedure when the assumptions of the latter are tenable.
The Effect of Additional Variables on Factor Indeterminacy in Models with a Single Common Factor
Authors: Mulaik Stanley A. , McDonald Roderick P.
Published: January 2006

“Determinate” solutions for the indeterminate common factor of p variables satisfying the single common factor model are not unique. Therefore an infinite sequence of additional variables that conform jointly with the original p variables to the original single common factor model does not determine a unique solution for the indeterminate factor of the p variables (although the solution is unique for the factor of the infinite sequence). Other infinite sequences may be found to determine different solutions for the factor of the original p variables. The paper discusses a number of theorems about the effects of additional variables on factor indeterminacy in a model with a single common factor and draws conclusions from them for factor theory in general.
Gapping
Authors: Wainer Howard , Schacht Stephen
Published: January 2006

Tukey's scheme for finding separations in univariate data strings is described and tested. It is found that one can use the size of a data gap coupled with its ordinal position in the distribution to determine the likelihood of its having arisen by chance. It was also shown that this scheme is relatively robust for fatter-tailed-than-Gaussian distributions and has some interesting implications in multidimensional situations.
Measuring Nominal Scale Agreement Between a Judge and a Known Standard
Authors: Wackerly D. D. , McClave J. T. , Rao P. V.
Published: January 2006

Two designs for comparing a judge's ratings with a known standard are presented and compared. Design A pertains to the situation where the judge is asked to categorize each of N subjects into one of r (known) classes with no knowledge of the actual number in each class. Design B is employed when the judge is given the actual number in each class and is asked to categorize the individuals subject to these constraints. The probability distribution of the total number of correct choices is developed in each case. A power comparison of the two procedures is undertaken.
A Generalization of Kristof's Theorem on the Trace of Certain Matrix Products
Authors: Ten Berge Jos M. F.
Published: January 2006

Kristof has derived a theorem on the maximum and minimum of the trace of matrix products of the form \documentclass[12pt]{minimal}
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$$X_1 \hat \Gamma _1 X_2 \hat \Gamma _2 \cdots X_n \hat \Gamma _n$$
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Best Linear Prediction of Composite Universe Scores
Authors: Jarjoura David
Published: January 2006

The problem of predicting universe scores for samples of examinees based on their responses to samples of items is treated. A general measurement procedure is described in which multiple test forms are developed from a table of specifications and each form is administered to a different sample of examinees. The measurement model categorizes items according to the cells of such a table, and the linear function derived for minimizing error variance in prediction uses responses to these categories. In addition, some distinctions are drawn between aspects of the approach taken here and the familiar regressed score estimates.
Some Types of Clustering with Relational Constraints
Authors: Ferligoj Anuška , Batagelj Vladimir
Published: January 2006

For the clustering problem with general (not necessarily symmetric) relational constraints, different sets of feasible clusterings, also called clustering types, determined by the same relation, can be defined. In this paper some clustering types are discussed and adaptations of the hierarchical clustering method compatible with these clustering types are proposed.