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Speaker: |
Ruth Etzioni, Ted Gooley, Yutaka Yasui |
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Abstract: |
In an effort to get to better know some of the
faculty and learn about research that is going on in the department, we've
invited 3 faculty members from |
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Speakers: |
Carolyn Rutter, Charles Kooperberg |
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Abstract: |
This is the second of two special seminars aimed at helping us meet
some of the faculty who we don't see often around the department. Three
faculty members will discuss their current research. Nancy Temkin is a
joint faculty member with Neurological Surgery, Carolyn Rutter
is with the Center for Health Studies at Group Health, and Charles Kooperberg is with |
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Title: |
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Speaker: |
David Lockhart, Graduate Student, Biostatistics |
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Abstract: |
David Lockhart will be giving the informal seminar talk
tomorrow. He will be discussing
statistical issues that arose in the analysis of an observational study examining
neuropsychological (NP) function and HIV-RNA levels in blood and
cerebrospinal fluid (CSF) among 25 patients at 3 time points before to two
months after initiating highly active antiretroviral therapy (HAART). Results for the full 25 subjects yielded
inconsistent associations at different time points; however, it appears this
may be to a change in the study protocol which introduced confounding between
time and the use of antiretroviral mono- or dual- therapy (ART) at baseline.. A subset
analysis of those who were not on ART at baseline revealed an association betweeen decreased CSF viral load and increased NP
scores, but the same associations were weaker and inconsistent for decreased
blood viral load and NP scores. Patients in this subset taking regimens including
drugs with good CNS penetration showed more improvement in NP scores, but did
not have larger drops in CSF viral load, than those whose regimens did not
contain any drugs. These results
suggest that the monitoring of CSF viral load and the use of CNS penetrant drugs may improve management of HIV-related
dementia, though further work is necessary to demonstrate the clinical
significance of these effects. |
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Title: |
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Speaker: |
Anton Westveld Graduate Student, Statistics |
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Abstract: |
Decision making under uncertainty has long been an area of interest
to a wide variety of academic disciplines: statistics, computer science, philosophy, political science, economics, and
biology, to name a few. The main mathematical method for examining multi-agent decision theory
has been game theory. However, the game theoretic solutions of some simple games
have been called into question, with a classic example being the Sub-Game
Perfect Nash Equilibrium (SPNE) of the centipede game. In experimental
settings, individuals rarely choose the SPNE solution (McKelvey and Palfrey (1992)). An explanation of this has been the notion of learning. As
individuals play the game, repeatedly, they will move toward the SPNE (Fudenberg and Tirole (1991)). An extensive amount of theoretical work has been written on
the subject, as well as, a limited amount of empirical work (El-Gamal, McKelvey, Palfrey (1993)). Recently, a general class of statistical models has
been developed allowing for a statistical interpretation of game theoretic
models (McKelvey and Palfrey (1996)). Within this
framework, it is possible to examine the statistical evidence for learning in
games. |
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Title: |
Of Mice and Men (and Cats) |
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Speaker: |
Bryan Shepherd Graduate Student, Biostatistics |
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Abstract: |
Bryan Shepherd will be giving
the informal seminar today. His talk
is titled
"Of Mice and Men (and Cats)".
He will be speaking about work he has been doing to estimate the
replication and differentiation rates of human hematopoietic stem cells.
Hematapoietic stem cells are the cells that
give rise to blood cells. These
parameters are fairly well known in mice and cats, but the methods
for identifying them in mice and cats cannot
be ethically performed on humans. Using relevant data from mice, cats, and humans, stochastic
models have been created aiming have been at identifying plausible values
for the replication and differentiation rates in
humans. In this presentation, some
of the statistical issues that have arisen.
This work is part of his RA with Peter Guttorp in the Statistics Department and Jan Abkowitz in the Hematology Department. |
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Title: |
Differential Item Functioning |
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Speaker: |
Lance Jolley Graduate Student, Biostatistics |
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Abstract: |
Tests with individually scored questions, or items, are commonplace in medical, educational, and sociological settings. To rely on the results of these tests, it is important to be certain that the tests
are free from bias to relevant subgroups.
Differential Item Functioning (DIF) occurs when subjects from different groups have differing
probabilities of success on an item, after controlling for overall
ability. Ways to detect DIF will be discussed with an emphasis on ordinal regression. Multiple comparison issues will also be addressed. My group has developed an
interactive STATA program to detect DIF. The Cognitive Assessment Screening Instrument (CASI) used for
dementia screening is used as an example. |
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Title: |
Some research
topics in health services research and diagnostic medicine |
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Speaker: |
Andrew Zhou |
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Abstract: |
In this talk, I will present a description of my current research in health services research and diagnostic medicine. I will describe some
research problems in analyses of health care costs, causal inferences in
observational studies and randomized trials with non-compliance, non-parametric
estimation of a receiver operating characteristic (ROC) curve, and correction
for verification bias in ROC curve studies. Finally, if I have time, I will also discuss some opportunities for biostatisticians in health services
research and clinical studies that are being conducted at the VA Puget Sound
Health Care System. |
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Title: |
Logistic Regression with Covariate Measurement Error: Estimation and a New Measurement Model |
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Speaker: |
Elizabeth Sugar, Graduate Student, Statistics |
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Abstract: |
One of the main focuses of Epidemiological research for the last
several decades has been the relationship between nutrient consumption and
disease risk. For example, several studies
have been done to try to determine whether or not there is a direct association between dietary fat
intake and breast cancer but there have often been conflicting results. One possible cause for such discrepancies is the presence of measurement
error in the covariates. When
attempting to deal with this problem we must address two issues: parameter estimation and modeling for the error structure. I
will give a brief background of the parameter estimation techniques which are commonly used along with a brief comparison of these methods. I will then then present our new measurement error model and discuss the extension of the estimating techniques to this new error structure. If there
is time I will briefly discuss the problem of sandard error
estimation for the parameters. |
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Title: |
Logistic Regression with Covariate Measurement Error: Estimation and a New Measurement Model |
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Speaker: |
Sierra Li, Graduate Student, Biostatistics |
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Abstract: |
One of the main focuses of Epidemiological research for the last
several decades has been the relationship between nutrient consumption and
disease risk. For example, several studies
have been done to try to determine whether or not there is a direct association between dietary fat
intake and breast cancer but there have often been conflicting results. One possible cause for such discrepancies is the presence of measurement
error in the covariates. When
attempting to deal with this problem we must address two issues: parameter estimation and modeling for the error structure. I
will give a brief background of the parameter estimation techniques which are commonly used along with a brief comparison of these methods. I will then then present our new measurement error model and discuss the extension of the estimating techniques to this new error structure. If there
is time I will briefly discuss the problem of sandard error
estimation for the parameters. |
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