Department of Statistics Seminar, Spring
2006
All the seminars are held in the meeting room of the
Department of Statistics (
Please contact Hongmei Jiang at hongmei@northwestern.edu if there is a speaker you would like to be invited to speak in this seminar.
Fall 2006
Schedule
Monday,
September 25, 2006, 11am
Professor
Ji-Ping Wang,
Department of Statistics, Northwestern University
Title: Statistical models for nucleosome DNA
alignment and linker length prediction in Eukaryotic cells
Abstract: Eukaryotic DNAs exist in a highly
compacted form known as chromatin. The nucleosome is the fundamental repeating
subunit of chromatin, formed by rapping a short tretch of DNA, 47bp in length,
around four pairs of istone proteins. Nucleosome DNA obtained by experiments
however varies in ength due to imperfect digestion. We develop a mixture model
that haracterizes the known dinucleotide periodicity probabilistically to
mprove the alignment of nucleosomal DNAs. To further investigate chromatin
tructure, we experimentally cloned and sequenced di-nucleosome sequences rom
yeast. Each dinucleosome sequence roughly cover two nucleosomes located toward
the two ends) with a linker DNA in between. A HMM model is rained based on the
nucleosome sequence alignment for prediction of ucleosome positioning. Results
show that Eukaryotic cells do favor periodic inker length in chromatin forming
on a roughly 10 bp basis.
Monday,
October 9, 2006, 11am
Professor Zhigang Zhang, Department of Statistics,
Monday,
October 23, 2006, 11am
Dr. Lanju Zhang, Department of Biostatistics, MedImmue
Inc.
Title: Response-Adaptive Randomization for Survival Trials: The
Parametric Approach
Abstract:
Few papers in the literature deal with response-adaptive
randomization procedures for survival outcomes and those that do either
dichotomize the outcomes or use a nonparametric approach. In this talk, the
optimal allocation approach and a parametric response-adaptive randomization
procedure are used under exponential and Weibull distributions. The optimal
allocations are derived for both distributions and the doubly-adaptive biased
coin design is applied to target the optimal allocations. The asymptotic
variance of the procedure is obtained for the exponential distribution. The
effect of intrinsic delay of survival outcomes is treated. These findings are
based on rigorous theory, but also verified by simulation. We illustrate our
procedure by redesigning a clinical trial.
Monday,
October 30, 2006, 11am
Professor Jan Hannig, Department of Statistics,
Title: Statistical Model for Tracking with Applications
Abstract: We propose a new
tracking model that allows for birth, death, splitting and merging of
targets. Targets are also allowed to go undetected for several frames. The
splitting and merging of targets is a novel addition for a statistically
based tracking model. This addition is essential for the tracking of storms,
which is the motivation for this work. The utility of
this tracking method extends well beyond the tracking of storms. It
can be valuable in other tracking applications that have splitting or
merging, such as vortexes, radar/ sonar signals, or groups of people. The
method assumes that the location of a target behaves like a Gaussian
Process when it is observable. A Markov Chain model decides when the
birth, death, splitting, or merging of targets takes place. The tracking
estimate is achieved by an algorithm that finds the tracks that maximize
the conditional density of the unknown variables given the data. The
problem of how to quantify the confidence in a tracking
estimate is addressed as well. Finally, some sufficient conditions
for consistency of this tracking estimate are presented and an almost sure
convergence of the tracking estimate to the true path is proved. The
practical suitability of this method is then demonstrated on
simulated and real data.
Based on a joint work with Thomas C.M. Lee and Curtis B. Storlie.
Monday,
November 6, 2006, 10am (Note: unusual time)
Professor Alfred Rademaker, Department
of Preventive Medicine, Feinberg
Title: The design and analysis of cancer clinical trials
Abstract:
Cancer clinical trials run the spectrum from Phase 0 feasibility
studies to Phase IV surveillance studies. This talk will focus on
statistical methods related to Phase I and Phase II clinical trials. For Phase
I, the standard 3+3 design as well as the continual reassessment method will be
discussed. For Phase II studies, the Simon 2-stage design will be
described, as well as the use of conditional methods for interval estimation of
response rate. Other design variations, such as randomized Phase II or
combined Phase II/Phase III studies, will also be presented.
Winter
2007 Schedule
Tuesday,
January 23, 2007, 2pm
Professor Joel Horowitz, Northwestern
University
Title:
Abstract:
Tuesday,
February 20, 2007, 2pm
Professor Ruey Tsay,
Title:
Abstract: