[ABE-L] Seminário

[Caio Lucidius Naberezny Azevedo]

Prezados,


Boa noite. Tenho o prazer de anunciar (abaixo) o próximo seminário do ciclo
de palestras do programa de Pós-Graduação em Estatística do IMECC-Unicamp.


Todos estão convidados.


Cordialmente,


Caio Azevedo (em nome da Comissão de Pós-Graduação)


*Local  e data: *sala 225 no dia 01/09/17 as 14h00.



*Apresentador:* Prof. Dr. Julio M. Stern



*Título: *Haphazard Intentional Allocation and Rerandomization to Improve
Covariate Balance in Experiments



*Autores:* by Marcelo S. Lauretto, Rafael B. Stern, Kari L. Morgan,
Margaret H. Clark, Julio M. Stern



*Abstract:* In randomized experiments, a single random allocation can yield
groups that differ meaningfully with respect to a given covariate.
Furthermore, it is only feasible to use classical control procedures of
allocation for a very modest number of covariates. As a response to this
problem, Morgan and Rubin [11, 12] proposed an approach based on
rerandomization (repeated randomization) to ensure that the final
allocation obtained is balanced. However, despite the benefits of the
rerandomization method, it has an exponential computational cost in the
number of covariates, for fixed balance constraints. Here, we propose the
use of haphazard intentional allocation, an alternative allocation method
based on optimal balance of the covariates extended by random noise, see
Lauretto et al. [7]. Our proposed method can be divided into a
randomization and an optimization step. The randomization step consists of
creating new (artificial) covariates according a specified distribution.
The optimization step consists of finding the allocation that minimizes a
linear combination of the imbalance in the original covariates and the
imbalance in the artificial covariates. Numerical experiments on real and
simulated data show a remarkable superiority of haphazard intentional
allocation over the rerandomization method, both in terms of balance
between groups and in terms of inference power.



-- 

===================================================
Assistant Professor,
Department of Statistics, Institute of Mathematics,
Statistics and Scientific Computing,
University of Campinas, Brazil.

Office Phone : 55 - 19 - 35216060
Fax : 55 - 19 - 3521-6094

home-page : http://www.ime.unicamp.br/~cnaber/
===================================================

"Pois desde a criação do mundo os atributos invisíveis de Deus, seu eterno
poder e sua natureza divina, têm sido observados claramente, podendo ser
compreendidos por intermédio de tudo o que foi criado, de maneira que tais
pessoas são indesculpáveis. "
Romanos 1:20
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