An extension of the partial credit model with an application to the measurement of change

The partial credit model is considered under the assumption of a certain linear decomposition of the item × category parameters _ih into basic parameters _j. This model is referred to as the linear partial credit model. A conditional maximum likelihood algorithm for estimation of the j is presented, based on (a) recurrences for the combinatorial functions involved, and (b) using a quasi-Newton approach, the so-called Broyden-Fletcher-Goldfarb-Shanno (BFGS) method; (a) guarantees numerically stable results, (b) avoids the direct computation of the Hesse matrix, yet produces a sequence of certain positive definite matricesB _k ,k=1, 2, ..., converging to the asymptotic variance-covariance matrix of the . The practicality of these numerical methods is demonstrated both by means of simulations and of an empirical application to the measurement of treatment effects in patients with psychosomatic disorders.The authors thank one anonymous reviewer for his constructive comments. Moreover, they thankfully acknowledge financial support by the Österreichische Nationalbank (Austrian National Bank) under Grant No. 3720.     

A spanish translation and validation of the daily stress inventory and a comparison of the level of stress experienced by three culturally distinct hispanic groups

Two studies were conducted, the first to establish a valid Spanish version of the Daily Stress Inventory (DSI). A second study was conducted using the bilingual version of the DSI to assess differences in the level of stress experienced by three selected Hispanic groups: (a) very Hispanic/Hispanic-oriented bicultural, (b) true bicultural, and (c) Anglo-oriented bicultural/very Anglicized as determined by the adapted version of the Acculturation Rating Scale for Mexican Americans (ARSMA). It was expected that stress levels would be highest for the least acculturated group. The results of the first study indicate that the Bilingual DSI scores are highly correlated with the scores of the original DSI when both instruments are responded to simultaneously by fully bilingual individuals. In Study 2, the initial data analyses showed no difference in the level of stress reported by Hispanics at different levels of acculturation as measured by the ARSMA. When a median-split method was employed, differences in the DSI I/E measures between the two groups were significant, suggesting that acculturation level may be related to stress level.     

Dimensionality and validity of two scales measuring different aspects of self-esteem

Two self-esteem (SE) scales aimed to measure self-esteem–conceptualized primarily (a) as the individual's ego-integrated libidinous and aggressive drives and their derivatives (Basic SE), and (b) as the need to earn self-esteem by competence and others' appraisal (Earning SE)–were developed and factor analysed. In order to construct- and cross-validate the scales, they were related to other well-known personality scales as well as to a projective technique (TAT) in two independent samples of first semester psychology students ( n = 153, n = 82). The empirical factor structure coincided well with the theoretical formulations. Basic SE showed concurrent validity being highly correlated ( p < 0.001) with both Rosenberg's and Coopersmith's self-esteem scales and highly or moderately with Neuroticism, Extraversion (EPQ) and Test-Anxicty (TAS) in both samples. Earning SE gained some construct validation by its relation to Type-A scores (JAS) as well as to verbal fantasy stories on TAT-pictures measuring Need of Achievement.     

Childhood stress: Perceptions of children and professionals

An assessment instrument was developed to measure children's perceptions of stressors in their lives, as well as their experiences and emotional reactions to these stressors. Two approaches from the adult literature, major life events and daily hassles, were compared for children. In addition, a comparison between children's and professionals' ratings of the severity of various stressors was made, as well as an examination of the relationship of experience and self-reported reaction to children's ratings. Results indicate that children's ratings of the severity of stressors do differ from adults', particularly when children have experienced the stressor. Further investigation in the study of childhood stress incorporating children's perceptions is proposed.     

THE BEHAVIOR OBSERVATION INSTRUMENT: A METHOD OF DIRECT OBSERVATION FOR PROGRAM EVALUATION1

The background and development of a multicategory direct observation system, the Behavior Observation Instrument (BOI), is described. This time-sampling procedure for recording the behavior of persons is demonstrated in several treatment settings and the results applied to issues of program evaluation. Elements that have prevented direct observation from being widely adopted, such as costs, manpower, and training requirements, are systematically analyzed. A basic psychometric analysis of the instrument is used to determine optimum frequency and duration of observation intervals as well as observer agreement. The results imply that direct observation methods, once assumed by some to belong to the special province of the single-subject design, can be used to assess the effects of programs on groups of psychiatric clients in an efficient and economic manner.     

An alternative to the methodology for analysis of covariance

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.Research reported in this paper has been partly supported by the Swedish Council for Social Science Research under project Statistical methods for analysis of longitudinal data, project director Karl G. Jöreskog, and partly by the Bank of Sweden Tercentenary Foundation under project Structural Equation Models in the Social Sciences, project director Karl G. Jöreskog.     

Spatial and conjoint models based on pairwise comparisons of dissimilarities and combined effects: Complete and incomplete designs

In pairwise multidimensional scaling, a spatial representation for a set of objects is determined from comparisons of the dissimilarity of any two objects drawn from the set to the dissimilarity of other pairs of objects drawn from that set. In pairwise conjoint scaling, comparisons among the joint effects produced by pairs of objects, where the objects in a pair are drawn from separate sets, are used to determine numerical representations for the objects in each set. Monte Carlo simulations of both pairwise dissimilarities and pairwise conjoint effects show that Johnson's algorithm can provide good metric recovery in the presence of high levels of error even when only a small percentage of the complete set of pairwise comparisons are tested.     

Axiomatic and numerical conjoint measurement: An evaluation of diagnostic efficacy

Synthetic data are used to examine how well axiomatic and numerical conjoint measurement methods, individually and comparatively, recover simple polynomial generators in three dimensions. The study illustrates extensions of numerical conjoint measurement (NCM) to identify and model distributive and dual-distributive, in addition to the usual additive, data structures. It was found that while minimum STRESS was the criterion of fit, another statistic, predictive capability, provided a better diagnosis of the known generating model. That NCM methods were able to better identify generating models conflicts with Krantz and Tversky's assertion that, in general, the direct axiom tests provide a more powerful diagnostic test between alternative composition rules than does evaluation of numerical correspondence. For all methods, dual-distributive models are most difficult to recover, while consistent with past studies, the additive model is the most robust of the fitted models.Douglas Emery is now at the Krannert Graduate School of Management, Purdue University, West Lafayette, IN, on leave from the University of Calgary.