9,252 research outputs found
On Bayesian Sequential Clinical Trial Designs
Clinical trials usually involve sequential patient entry. When designing a
clinical trial, it is often desirable to include a provision for interim
analyses of accumulating data with the potential for stopping the trial early.
We review Bayesian sequential clinical trial designs based on posterior
probabilities, posterior predictive probabilities, and decision-theoretic
frameworks. A pertinent question is whether Bayesian sequential designs need to
be adjusted for the planning of interim analyses. We answer this question from
three perspectives: a frequentist-oriented perspective, a calibrated Bayesian
perspective, and a subjective Bayesian perspective. We also provide new
insights into the likelihood principle, which is commonly tied with statistical
inference and decision making in sequential clinical trials. Some theoretical
results are derived, and numerical studies are conducted to illustrate and
assess these designs
The Ci3+3 Design for Dual-Agent Combination Dose-Finding Clinical Trials
We propose a rule-based statistical design for combination dose-finding
trials with two agents. The Ci3+3 design is an extension of the i3+3 design
with simple decision rules comparing the observed toxicity rates and
equivalence intervals that define the maximum tolerated dose combination. Ci3+3
consists of two stages to allow fast and efficient exploration of the
dose-combination space. Statistical inference is restricted to a beta-binomial
model for dose evaluation, and the entire design is built upon a set of fixed
rules. We show via simulation studies that the Ci3+3 design exhibits similar
and comparable operating characteristics to more complex designs utilizing
model-based inferences. We believe that the Ci3+3 design may provide an
alternative choice to help simplify the design and conduct of combination
dose-finding trials in practice
Optimal control-based inverse determination of electrode distribution for electroosmotic micromixer
This paper presents an optimal control-based inverse method used to determine
the distribution of the electrodes for the electroosmotic micromixers with
external driven flow from the inlet. Based on the optimal control method, one
Dirichlet boundary control problem is constructed to inversely find the optimal
distribution of the electrodes on the sidewalls of electroosmotic micromixers
and achieve the acceptable mixing performance. After solving the boundary
control problem, the step-shaped distribution of the external electric
potential imposed on the sidewalls can be obtained and the distribution of
electrodes can be inversely determined according to the obtained external
electric potential. Numerical results are also provided to demonstrate the
effectivity of the proposed method
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