BILOG is the defacto standard for dichotomous IRT model estimation. However, BILOG is a commercial product and limited in other ways. Hanson provides an open-source alternative, ICL, and this paper compares ICL to BILOG in terms of features and obtained item parameter estimates. In general, BILOG has more features, especially with respect to assessing model-data fit. One notable feature of ICL ...

Aiming at a unified view of the logics describing spatial structures, we introduce a general framework, BiLog, whose formulae characterise monoidal categories. As a first instance of the framework we consider bigraphs, which are emerging as a an interesting (meta-)model for spatial structures and distributed calculi. Since bigraphs are built orthogonally on two structures, a hierarchical place ...

This paper compares three methods of item calibration—concurrent calibration, separate calibration with linking, and fixed item parameter calibration—that are frequently used for linking item parameters to a base scale. Concurrent and separate calibrations were implemented using BILOG-MG. The Stocking and Lord (1983) characteristic curve method of parameter linking was used in conjunction with ...

Spatial Logics have been recently proposed as modal logics inspecting the ‘spatial’ nature of models (as opposed to ‘temporal logics’ inspecting model behavior). Spatial Logics, essentially, lift constructors (and structural properties) of underlying models to the logical level, obtaining new ‘spatial’ logical connectives. The semantics of spatial logics is model dependant: different properties...

Bigraphs are emerging as a (meta-)model for concurrent calculi, like CCS, ambients, πcalculus, and Petri nets. They are built orthogonally on two structures: a hierarchical place graph for locations and a link (hyper-)graph for connections. Aiming at describing bigraphical structures, we introduce a general framework, BiLog, whose formulae describe arrows in monoidal categories. We then instant...

Parameters of the two-parameter logistic model are generally estimated via the expectation-maximization algorithm, which improves initial values for all parameters iteratively until convergence is reached. Effects of initial values are rarely discussed in item response theory (IRT), but initial values were recently found to affect item parameters when estimating the latent distribution with ful...

We examined Myers-Briggs Type Indicator (MBTI) score distributions computed using itemresponse theory (IRT) to assess the generalizability of earlier bimodality reports which have been cited in support of the “type” versus “trait” view of personality. Using the BILOG IRT program to score a sample of approximately 12,000 individuals who participated in leadership development programs, θ score di...

Since its release in 1976, Wingersky, Barton, and Lord's (1982) LOGIST has been the most widely used computer program for estimating the parameters of the 3-parameter logistic (Birnbaum) item response model.. An alternative program, Mislevy and Bock's (1983) BILOG, has recently become available. This paper compares the approaches taken by the two programs, and offers some initial guidelines for...