American Statistical Association
New York City
Metropolitan Area Chapter

The Child Study Center
At NYU Langone Medical Center
Division of Biostatistics
Lectures on Analysis of Neuroimaging Data



Armin Schwartzman, Ph.D.
Associate Professor of Statistics
North Carolina State University

THE PROBLEM OF VOXELWISE INFERENCE UNDER CORRELATION

The traditional voxelwise inference scheme entails computation of a test statistic at each voxel and thresholding so that a global error rate is controlled. This scheme implicitly assumes that most voxels behave according to the null distribution and that the test statistics are at most locally dependent. Under these assumptions, a histogram of the observed test statistics should have a large component that follows the null distribution. Data from neuroimaging studies, however, often contradict this, producing shifted and scaled histograms. In this talk, I review some of my own investigations into this phenomenon and describe how high correlation: 1) can affect false discovery rate inference, making it more variable and more conservative; and 2) can sometimes explain most of the histogram behavior even in the presence of no signal. In the latter situation, I show that this can be achieved by a latent factor model, of which Efron's empirical null is a special case.


Date: Tuesday, November 18, 2014
Time: 4:00 P.M.
Location: NYU Deptartment of Child & Adolescent Psychiatry
“Central Park” meeting area at the Child Study Center
One Park Avenue (between 32nd and 33rd Streets)
7th Floor
New York, New York

The Series is open to all; RSVPs are requested.
Due to new security procedures at One Park Ave., those wishing to attend
who do not have an NYU ID are required to RSVP.
To do so, please contact Cielo Diaz at cielo.diaz@nyumc.org or 646-754-5195.


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