Tol is a programming language dedicated to the world of statistics and focused on time series analysis and stochastic processes. Unlike many other languages, Tol is not an object-oriented language, but a declarative language driven by functions, based on two key features: simple syntactical rules and a powerful set of extensible data types.
gfit analyzes data using models. gfit lets the user create a model for virtually any type of system using a minimal amount of computer code. It is particularly useful for studying various systems in biophysics, biochemistry, and cell biology. The interface for gfit models specifies relationships between input and output variables in a rule-based fashion. It provides flexibility and allows the user to reuse same models for many related problems.
PED is a dialogue management system that uses a probabilistic nested belief model to choose dialogue strategies. The dialogue system designer need only supply a set of plan rules to PED as a dialogue grammar with preconditions. Using this grammar, PED constructs game trees (like the one below) to represent the outcomes of the dialogue, so that a dialogue strategy can be chosen for the current turn in the dialogue. PED automatically maintains a belief model by a belief revision process that uses the observed acts in the dialogue. The game tree is evaluated in the context of this belief model. PED is efficient because it uses probabilistic estimates of belief rather than a plain logical belief model.
The Item Response Theory (IRT) library is a set of functions to estimate the items and abilities from the responses of subjects to a questionnaire. The IRT models supported are the logistic model, the nominal response model, the graded response model, and smoothing by penalization and kernel. The project also hosts rirt, a package for the R Project for Statistical Computing, and eirt, an add-in for Excel.
Libgvectors is a C++ library for visualizing three dimensional mathematical vectors, providing three fundamental classes for achieving its purpose. It makes as few assumptions as possible about the graphics library used to draw vectors on a screen and is not bound to any particular graphics library.