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Nonlinear sequential designs for logistic item response theory models with applications to computerized adaptive tests
Computerized adaptive testing is becoming increasingly popular due to
advancement of modern computer technology. It differs from the conventional
standardized testing in that the selection of test items is tailored to
individual examinee's ability level. Arising from this selection strategy is a
nonlinear sequential design problem. We study, in this paper, the sequential
design problem in the context of the logistic item response theory models. We
show that the adaptive design obtained by maximizing the item information leads
to a consistent and asymptotically normal ability estimator in the case of the
Rasch model. Modifications to the maximum information approach are proposed for
the two- and three-parameter logistic models. Similar asymptotic properties are
established for the modified designs and the resulting estimator. Examples are
also given in the case of the two-parameter logistic model to show that without
such modifications, the maximum likelihood estimator of the ability parameter
may not be consistent.Comment: Published in at http://dx.doi.org/10.1214/08-AOS614 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Level sets of multiple ergodic averages
We propose to study multiple ergodic averages from multifractal analysis
point of view. In some special cases in the symbolic dynamics, Hausdorff
dimensions of the level sets of multiple ergodic average limit are determined
by using Riesz products.Comment: This note was refused by Proceedings of AMS although the referee said
"In my opinion this is a nice application of the Riesz product technique to
solve, in principle, a hard problem when considered in its full generality.
Nevertheless, I think it needs some extra work to see how this example seats
in a more general context and explore how far this technique can go." We
should say that Riesz product works perfectly in the situation described in
this note, but Riesz product has its limit--we don't think that Riesz product
technique can solve the problem in its generalit
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