The essential feature of controlled clinical trials is the random assignment of subjects to two or more treatment groups under investigation. The principle of randomization provides a protection against hidden biases and thus increases the validity of the trial’s findings. Another fundamental aspect of clinical trials is the incorporation into the design and/or analysis those prognostic factors...

We prove a Central Limit Theorem for the sequence of random compositions of a two-color randomly reinforced urn. As a consequence, we are able to show that the distribution of the urn limit composition has no point masses.

The User Requirements Notation (URN) combines the Goaloriented Requirement Language (GRL) with the Use Case Map (UCM) scenario notation. Although tools exist in isolation for both views, they are currently not meant to work together, hence preventing one to exploit URN to its fullest extent. This paper presents jUCMNav, a new Eclipse-based tool that supports both UCM and GRL in an integrated wa...

Strengthening the teaching of probability requires an adequate training prospective teachers, which should be based on prior assessment their knowledge. Consequently, aim this study was to analyse how 139 Spanish mathematics teachers relate classical and frequentist approaches probability. To achieve goal, content analysis used categorize teachers’ answers a questionnaire with open-ended tasks ...

The list of physically motivated urn models that can be solved in terms classical orthogonal polynomials is very small. It includes a model proposed by D. Bernoulli and further analyzed S. Laplace P. T. Ehrenfest eventually connected with the Krawtchouk Hahn polynomials. This connection was reversed recently case Jacobi where rather contrived, later simpler proposed. Here we consider an going J...

The Pólya process is an urn scheme arising in the context of the contagion spreading. It exhibits unstable persistence effects. The Friedman urn process is dual to the Pólya one with antipersistent stabilizing effects. It appears in a safety campaign problem. A Pólya-Friedman urn process is investigated with a tuning persistence parameter extrapolating the latter two extreme processes. The stud...

This study investigates the effects of grid resolution on hydroacoustic performance benchmark INSEAN E779A propeller operated in uniform flow, open water and non-cavitating conditions. In numerical calculations, an incompressible hydrodynamic solver together with porous FW-H (Ffowcs-Williams Hawkings) equation is used to predict URN (Underwater Radiated Noise). The first aim within this explore...

SUMMARY An urn model of Diaconis and some generalizations are discussed. A convergence theorem is proved that implies for Diaconis' model that the empirical distribution of balls in the urn converges with probability one to the uniform distribution.

We prove a Central Limit Theorem for the sequence of random compositions of a two-color randomly reinforced urn. As a consequence, we are able to show that the distribution of the urn limit composition has no point masses.

In this article we review the important statistical properties of the urn randomization (design) for assigning patients to treatment groups in a clinical trial. The urn design is the most widely studied member of the family of adaptive biased-coin designs. Such designs are a compromise between designs that yield perfect balance in treatment assignments and complete randomization which eliminate...