An Extension of Testlet-Based Equating to the Polytomous Testlet Response Theory Model

Educational assessments tests are often constructed using testlets because of the flexibility to test various aspects of the cognitive activities and broad content sampling. However, the violation of the local item independence assumption is inevitable when tests are built using testlet items. In this study, simulations are conducted to evaluate the performance of item response theory models and testlet response theory models for both the dichotomous and polytomous items in the context of equating tests composed of testlets. We also examine the impact of testlet effect, length of testlet items, and sample size on estimating item and person parameters. The results show that more accurate performance of testlet response theory models over item response theory models was consistently observed across the studies, which supports the benefits of using the testlet response theory models in equating for tests composed of testlets. Further, results of the study indicate that when sample size is large, item response theory models performed similarly to testlet response theory models across all studies.

Toward a “Standard Model” of Early Language Learning

A standard model is a theoretical framework that synthesizes observables into a quantitative consensus. Have researchers made progress toward this kind of synthesis for children’s early language learning? Many computational models of early vocabulary learning assume that individual words are learned through an accumulation of environmental input. This assumption is also implicit in empirical work that emphasizes links between language input and learning outcomes. However, models have typically focused on average performance, whereas empirical work has focused on variability. To model individual variability, we relate the tradition of research on accumulator models to item response theory models from psychometrics. This formal connection reveals that currently available data sets do not allow researchers to test the resulting models fully, illustrating a critical need for theory to contribute to shaping new data collection and creating and testing an eventual standard model.

Recent developments of parameter estimation methods in item response theory models

This research reviewed the recent development of parameter estimation methods in item response theory models. Various new methods to manage the computational burden problem with respect to the item factor analysis and multidimensional item response models, which have high dimensional factors, were introduced. Monte Carlo integral methods, approximation methods for marginal likelihood, new optimization methods, and techniques used in the machine learning field were employed for the estimation methods. Theoretically, a new type of asymptotical setting, that assumes infinite number of sample sizes and items, was considered. Several methods were classified apart from the maximum likelihood method or Bayesian method. Theoretical development of interval estimation methods for individual latent traits were also proposed and they provided highly accurate intervals

Evaluation of the psychometric properties of the burn specific health scale-brief: A National Institute on Disability, Independent Living, and Rehabilitation Research Burn Model System Study

Objective The Burn Specific Health Scale-Brief (BSHS-B) is a commonly used burn specific health outcome measure that includes 40 items across nine subscales. The objective of this study was to use both classical and modern psychometric methods to evaluate psychometric properties of the BSHS-B. Methods Data were collected post burn injury by a multisite federally funded project tracking long term outcomes. We examined dimensionality, local dependence, item fit, and functioning of response categories, homogeneity, and floor and ceiling effects. Items were fit to Item Response Theory models for evaluation. Results A total of 653 adults with burn injury completed the BSHS-B. Factor analyses supported unidimensionality for all subscales, but not for a total score based on all 40 items. All nine of the subscales had significant ceiling effects. Six item pairs displayed local dependence suggesting redundance and 11 items did not fit the Item Response Theory models. At least 15 items have too many response options. Conclusions Results identified numerous psychometric issues with the BSHS-B. A single summary score should never be used for any purpose. Psychometric properties of the scale need to be improved by removing redundant items, reducing response categories and modifying or deleting problematic items. Additional conceptual work is needed to, at a minimum, revise the work subscale and optimally to revisit and clearly define the constructs measured by all the subscales. Additional items are needed to address ceiling effects.

The Structure of Developmental Variation in Early Childhood

Do children’s abilities develop in tandem or on their own separate timetables? Piaget proposed that development proceeded globally through stages; more recent theories view development as more modular with different abilities developing independently and on different time-scales. The developmental differentiation hypothesis suggests that the structure of a child’s development is unitary early in infancy but becomes more complex with age. Despite an abundance of theoretical interest in this question, there is little empirical work on the macrostructure of developmental changes in early childhood. We investigate this structure using two large datasets of parent-reported developmental milestones. Applying item response theory models, we find that variation in development across infancy and early childhood is multidimensional. Consistent with the differentiation hypothesis, differences among older children are better described by higher-dimensional models. In addition, in longitudinal data, we find that, within-person changes in underlying abilities are highly coupled early in life but their coupling decreases by age 12 months. Our work provides a model-based method for linking holistic descriptions of early development to basic theoretical questions about the nature of change in childhood.