We study the properties of false discovery rate (FDR) thresholding, viewed as
a classification procedure. The "0"-class (null) is assumed to have a known,
symmetric log-concave density while the "1"-class (alternative) is obtained
from the "0"-class either by translation (location model) or by scaling (scale
model). Furthermore, the "1"-class is assumed to have a small number of
elements w.r.t. the "0"-class (sparsity). Non-asymptotic oracle inequalities
are derived for the excess risk of FDR thresholding.
When testing a large number of independent hypotheses, three different
questions are of interest: are some hypotheses true alternatives? How many of
them? Which of them? These questions give rise to a detection, an estimation,
and a selection problem. Recent work demonstrates the existence of intrinsic
bounds in these problems: detection and estimation boundaries in sparse
location models, and criticality for the selection problem. We study
consequences of such limitations in terms of power of False Discovery Rate
(FDR) controlling procedures.