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liboscats Reference Manual | ![]() |
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Top | Description | Object Hierarchy |
struct OscatsModelL3p;
The Three-Paramter Logistic IRT model: P(X=1|theta) = c + (1-c)/1+exp[-(sum_i a_i theta_i -b + sum_j d_j covariate_j)], where a_i are the item discrimination for each dimension and b is the scaled item difficulty. Note that this differs from the usual IRT parameterization c + (1-c)/1+exp[-a(theta-b)]. Distance is defined as: abs(sum_i a_i theta_i - b + sum_j d_j covariate_j).
Parameter names: Diff, Guess, Discr.DimName
References: