Alternative Approaches to Addressing Non-Normal Distributions in the Application of IRT Models to Personality Measures

It is generally assumed that the latent trait is normally distributed in the population when estimating logistic item response theory (IRT) model parameters. This assumption requires that the latent trait be fully continuous and the population homogenous (i.e., not a mixture). When this normality assumption is violated, models are misspecified, and item and person parameter estimates are inaccurate. When normality cannot be assumed, it might be appropriate to consider alternative modeling approaches: (a) a zero-inflated mixture, (b) a log-logistic, (c) a Ramsay curve, or (d) a heteroskedastic-skew model. The first 2 models were developed to address modeling problems associated with so-called quasi-continuous or unipolar constructs, which apply only to a subset of the population, or are meaningful at one end of the continuum only. The second 2 models were developed to address non-normal latent trait distributions and violations of homogeneity of error variance, respectively. To introduce these alternative IRT models and illustrate their strengths and weaknesses, we performed real data application comparing results to those from a graded response model. We review both statistical and theoretical challenges in applying these models and choosing among them. Future applications of these and other alternative models (e.g., unfolding, diffusion) are needed to advance understanding about model choice in particular situations.     

Asymptotic confidence intervals for the Pearson correlation via skewness and kurtosis

When bivariate normality is violated, the default confidence interval of the Pearson correlation can be inaccurate. Two new methods were developed based on the asymptotic sampling distribution of Fisher's z′ under the general case where bivariate normality need not be assumed. In Monte Carlo simulations, the most successful of these methods relied on the (Vale & Maurelli, 1983, Psychometrika, 48, 465) family to approximate a distribution via the marginal skewness and kurtosis of the sample data. In Simulation 1, this method provided more accurate confidence intervals of the correlation in non-normal data, at least as compared to no adjustment of the Fisher z′ interval, or to adjustment via the sample joint moments. In Simulation 2, this approximate distribution method performed favourably relative to common non-parametric bootstrap methods, but its performance was mixed relative to an observed imposed bootstrap and two other robust methods (PM1 and HC4). No method was completely satisfactory. An advantage of the approximate distribution method, though, is that it can be implemented even without access to raw data if sample skewness and kurtosis are reported, making the method particularly useful for meta-analysis. Supporting information includes R code.     

The Bible, Knowledge of God and Dei Verbum

How may an inquiring person fittingly look upon the Bible? In what manner can a person's attention to the Bible assist them to knowledge? For a Catholic Christian analysis, what ideas are suitable about the place of the Bible in relations between God and humans, and in appropriation by a person today of whatever divine disclosure or revelation is at hand? This article outlines reflections on these matters. Links are apparent with key points in Vatican II’s Dei Verbum. The first of four sections concerns a fundamentalist outlook. Section II has to do with certain limited but significant ways in which a person may look on the Bible: ways similar to ways in which a person may look on other texts. Section III pauses on inquiries into ‘deep, inner’ matters of life where the person inquiring does not proceed from a perspective of Catholic Christian faith. Section IV surveys a broad range of thoughts that may aptly be endorsed from within a perspective of Catholic Christian faith. The thoughts concern the nature of the situation by which a Catholic Christian person today can advance in knowledge of God: in appropriation of divine disclosure. Ways in which a person may look on the Bible that go beyond those exhibited earlier are now made explicit. (The article fully allows that numerous views held by one or another follower of Jesus who does not adhere to Roman Catholicism may, in respects at stake, harmonize with a Catholic Christian faith‐perspective.)     

Teaching social‐learning procedures to paraprofessionals working with individuals with severe mental illness in a maximum‐security forensic hospital

This study describes an integrated technical method for teaching learning‐based interventions to paraprofessionals working in a maximum‐security psychiatric facility as a social‐learning program was implemented. This training approach combines brief didactic instruction with live demonstration and guided practice in specific procedures. Comparisons between baseline and post‐training functioning of staff were made using ongoing direct observational assessment data. Results revealed that following training and program implementation staff were much more active overall, interacted with clients far more often, and engaged in much lower rates of job‐irrelevant activity. Moreover, following training direct observational data of the patterns of staff–client interactions showed that staff were much more likely to demonstrate interactions reflective of learning‐based interventions than at baseline. These results have important implications for clinicians and administrators attempting to implement behavioral rehabilitation programs. Copyright © 2001 John Wiley & Sons, Ltd.     

Emotional content of talk to the fetus and healthy coping behaviors during pregnancy

This study examined whether the emotional content of talk to the self and to the fetus were related to health behaviors and psychosocial factors during pregnancy. One hundred fifty-two third-trimester pregnant women attending childbirth preparation classes completed a survey containing the Intrapersonal Communication Questionnaire, which sampled spontaneous talk to the self (self-talk) and to the fetus (baby-talk), and which yielded ratings of emotional valence of talk quotations into positive, negative, neutral, and mixed categories; the Rosenberg Self-Esteem Scale; and indices for life stress, social support, and consumption behaviors. Baby-talk was more positive whereas self-talk was more negative, or emotionally distressed. More mixed baby-talk occurred with more medicine consumption, and medicine consumption was also related to lower self-esteem and more life stress. More negative baby-talk occurred when cigarette and caffeine consumption was higher. Emotional content of maternal talk to the fetus might indicate development of maternal bonding, and specific emotional contents might be related to health-relevant coping behaviors, for example, consumption of cigarettes and caffeine. Clinical implications for maternal behaviors after birth are discussed.     

Visual working memory for global,object, and part-based information

We investigated visual working memory for novel objects and parts of novel objects. After a delay period, participants showed strikingly more accurate performance recognizing a single whole object than the parts of that object. This bias to remember whole objects, rather than parts, persisted even when the division between parts was clearly defined and the parts were disconnected from each other so that, in order to remember the single whole object, the participants needed to mentally combine the parts. In addition, the bias was confirmed when the parts were divided by color. These experiments indicated that holistic perceptual-grouping biases are automatically used to organize storage in visual working memory. In addition, our results suggested that the bias was impervious to top-down consciously directed control, because when task demands were manipulated through instruction and catch trials, the participants still recognized whole objects more quickly and more accurately than their parts. This bias persisted even when the whole objects were novel and the parts were familiar. We propose that visual working memory representations depend primarily on the global configural properties of whole objects, rather than part-based representations, even when the parts themselves can be clearly perceived as individual objects. This global configural bias beneficially reduces memory load on a capacity-limited system operating in a complex visual environment, because fewer distinct items must be remembered.     

Probabilistic retroactive interference: the role of accessibility bias in interference effects

Probabilistic retroactive interference (RI) refers to the interfering effects of intermixing presentations of an earlier studied response (A-B) with presentations of a competing response (A-D). As an example, for a 2/3 condition, a cue word was presented with its earlier studied response twice and its competing response once during the interference phase. Performance on direct and indirect tests of memory for earlier studied responses was combined to reveal dissociations between effects on recollection and accessibility bias. Manipulating probabilistic RI influenced accessibility bias but left recollection unchanged. Effects of probabilistic RI were compared with effects of traditional, nonprobabilistic RI. The authors contrast their dual-process model with traditional accounts of RI and discuss the importance of distinguishing between recollection and accessibility bias for understanding interference effects.