Threeparameter
Threeparameter is a term used to describe models or distributions that are specified by three free parameters. It does not refer to a single canonical model, but rather to a class of three-parameter families encountered across statistics, psychometrics, and reliability engineering. The extra parameter relative to two-parameter families provides additional flexibility to capture features such as shift, asymmetry, or guessing behavior.
In distribution theory, three-parameter families extend two-parameter forms by including a location or threshold parameter in
In psychometrics, the three-parameter logistic model (3PL) is a prominent application in item response theory. It
Estimation of three-parameter models typically uses maximum likelihood or Bayesian methods. Challenges include identifiability and interpretability