Informal Seminars Presented In Winter 2001

 

January 10, 2001

 

Title: 

My RA in Nairobi - Incidences of opportunistic diseases in a cohort of HIV infected adults

Speakers:

Bryan Shepherd, Graduate student, Biostatistics

Abstract: 

I spent this past summer in Nairobi, Kenya. In addition to seeing quite a bit of East Africa, I was involved in a couple AIDS related studies. One of them looked at diseases that invade HIV-infected individuals because of their weakened immune system. A cohort of HIV-positive people was followed for 3 years and my job was to take the data from this cohort and write a paper. I didn't find the cure for AIDS, but I came across many ethical, data, and statistical issues that I found interesting.

 

 



 

January 17, 2001

 

Title: 

Network meta-analysis for indirect treatment comparisons

Speakers:

Thomas Lumley, Assistant Professor, Biostatistics

Abstract: 

I present methods for assessing the relative effectiveness of two treatments when they have not been compared directly in a randomized trial but have each been compared to other treatments. These network metanalysis techniques allow estimation of both heterogeneity in the effect of any given treatment and inconsistency ("incoherence") in the evidence from different pairs of treatments. A simple estimation procedure using linear mixed models is given, and used in a meta-analysis of treatments for acute myocardial infarction.

 

 



 

January 24, 2001

 

Title: 

Spatio-temporal Bayesian hierarchical models for mapping disease rates

Speaker:

Erin Conlon, Biostatistics

Abstract: 

Hierarchical models provide a mechanism for stabilizing disease rate estimates from small areas, while maintaining geographic resolution. Spatial correlation among rates is possible, due to unobserved covariates such as environmental or socio-economic effects. Spatial variation is incorporated into the hierarchical model through random effects with a spatial prior structure. In such a model, regional rate estimates are stabilized by combining information from neighboring regions. In many past applications, the neighborhood definition was fixed a priori as regions sharing a common boundary. We use two methods for generalizing the neighborhood structure that allow the data to inform on the strength and geographic extent of spatial similarity. We compare posterior parameter estimates and model fit for the various approaches using 21 years of lung cancer mortality data in counties in the state of Ohio.

 

 



 

February 21, 2001

 

Title: 

What if the number of 'things' we don't know is one of the things we don't know?

Speaker:

Chuan Zhou, Graduate student, Biostatistics

Abstract: 

Recent advances in technology have generated enormous data sets such as satellite data, climate data, web-site visiting information and, of course, microarray data. Often the volume of these data sets prevent us from extracting information directly. Cluster analysis is now recognized by many researchers as an important and useful tool for data mining. However, inferring the number of clusters (components) underlying the data remains a practical and theoretically challenging problem. This is more often a scientific question rather than a statistical question. In this talk, I will give a survey of the various ways to estimate the number of clusters in "classical" clustering and model-based clustering frameworks. Discussion and feedbacks are most welcome.

 

 



 

March 7, 2001

 

Title: 

Aspects of cancer biomarker development

Speaker:

Margaret Pepe, Professor, Biostatistics

Abstract: 

Recent advances in biotechnology, including expression-array methodology, proteomics and immunology, promise to yield biomarkers for early detection of cancer. Population cancer screening based on such biomarkers could greatly impact on the mortality and morbidity associated with cancer. Biomarker development is a relatively new field for the research community. Guidelines are needed to guide the development process. We propose that biomarker development be structured into 5 distinct consecutive phases of research: Phase 1, the initial exploratory phase to identify potentially promising markers; Phase 2, the clinical assay development and validation phase, using clinical specimens from cases with established disease and suitable controls; Phase 3, the phase that determines if the biomarker detects disease early, before it becomes clinically evident, using specimens from clinical repositories; Phase 4, the initial prospective population screening phase that establishes the number and nature of cancers detected; and Phase 5, the cancer-control phase, that determines the net benefits and costs of the biomarker based population cancer screening program. For each phase, we outline objectives and key elements of study design. Rigorous and efficient development of useful biomarkers is likely to be facilitated by a structured approach, as is already in place for therapeutic drug development. Criteria are now needed for determining when a biomarker has successfully completed one phase and can proceed to the next. 

 

  



Last Modification: 29 November 2001