An Alternative Three-Parameter Logistic Item Response Model IRT
- Author(s):
- Pashley, Peter J.
- Publication Year:
- 1991
- Report Number:
- RR-91-10
- Source:
- ETS Research Report
- Document Type:
- Report
- Page Count:
- 36
- Subject/Key Words:
- Item Response Theory (IRT), Mathematical Models, Statistical Analysis
Abstract
Birnbaum's three-parameter logistic function has become a common basis for item response theory modeling, especially within situations where significant guessing behavior is evident. This model is formed through a linear transformation of the two-parameter logistic function in order to facilitate a lower asymptote. This paper discusses an alternative three-parameter logistic model in which the asymptote parameter is a linear component within the logit of the function. This alternative is derived from a more general four-parameter model based on a transformed hyperbola. (36pp.)
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- http://dx.doi.org/10.1002/j.2333-8504.1991.tb01376.x