Title
The Tau-Path Method of Screening for Monotone Association in Subpopulations
Speaker
Joe Verducci, The Ohio State University
Abstract
The screening problem here is to search through many pairs of variables that have been measured on a common sample, identifying pairs that are likely to have a structural relationship on some subset of the sample. An example is the screening of thousands of medicinal compounds, whose biological activity (Growth Inhibition) has been measured on 60 cancer cell-lines curated by the National Cancer Institute (NCI-60), against expression levels of hundreds of microRNA (miR), which have recently been measured on the same NCI-60 sample. It is believed that miRs play a role in the chemo-sensitivity and chemo-resistance of cells, but it would be extraordinarily expensive to conduct dilution assays for all compounds on cells with each mir individually silenced or stimulated. Thus there is a need for screening a manageable number of compound-miR pairs for further experimentation.
The statistical approach involves a modification of Kendall's tau test for independence, where observations are re-ordered according to their components of concordance. The re-ordered components form a path whose distribution is simulated under the null hypothesis of independence to establish an acceptance region. Excursions outside this region indicate highly associated subsets. This tau-path method has better power than Kendall's test when the alternative involves a small but highly associated subpopulation. In this type situation, it also performs better than several other ad hoc methods, including tests based only on the longest monotone subsequence, and tests involving transformations to a location shift problem.
This is joint work with Li Yu, Paul Blower and Shili Lin.
Meet the speaker in Room 212 Cockins Hall at 4:30 p.m. Refreshments will be served.
