Accession Number : ADA198128

Title :   Nonparametric Estimation of a Latent Trait Density.

Descriptive Note : Technical rept. 1 Aug 85-30 Dep 86,

Corporate Author : MISSOURI UNIV-COLUMBIA DEPT OF STATISTICS

Personal Author(s) : Speckman, Paul L

PDF Url : ADA198128

Report Date : 31 Jul 1988

Pagination or Media Count : 30

Abstract : A method for estimating the density of the latent trait (or ability) in an item response model is given based on the logspline density estimator of Stone and Koo. In the implementation presented here, families of densities whose logarithms are quadratic splines are used to estimate the unknown latent trait density. The number of knots in the spline is variable permitting arbitrary densities to be well approximated from the logspline family. Because the family is exponential and contains all normal distributions, the likelihood ratio test can be used to test for normality. An ad hoc method is proposed for choosing the number of knots, and the method is illustrated with two simulated data sets. (KR)

Descriptors :   *ESTIMATES, *DENSITY, *NONPARAMETRIC STATISTICS, DATA BASES, MATHEMATICAL MODELS, NORMAL DISTRIBUTION, NORMALITY, QUADRATIC EQUATIONS, RESPONSE, SIMULATION, SPLINES(GEOMETRY)

Subject Categories : Statistics and Probability

Distribution Statement : APPROVED FOR PUBLIC RELEASE