  This book is a collection of papers dedicated to the memory of Yehuda Vardi.
Yehuda was the chair of the Department of Statistics of Rutgers University when
he passed away unexpectedly on January 13, 2005. On October 21--22, 2005, some
150 leading scholars from many different fields, including statistics,
telecommunications, biomedical engineering, bioinformatics, biostatistics and
epidemiology, gathered at Rutgers in a conference in his honor. This conference
was on ``Complex Datasets and Inverse Problems: Tomography, Networks, and
Beyond,'' and was organized by the editors. The present collection includes
research work presented at the conference, as well as contributions from
Yehuda's colleagues. The theme of the conference was networks and other
important and emerging areas of research involving incomplete data and
statistical inverse problems. Networks are abundant around us: communication,
computer, traffic, social and energy are just a few examples. As enormous
amounts of network data are collected in this information age, the field has
attracted a great amount of attention from researchers in statistics and
computer engineering as well as telecommunication providers and various
government agencies. However, few statistical tools have been developed for
analyzing network data as they are typically governed by time-varying and
mutually dependent communication protocols sitting on complicated
graph-structured network topologies. Many prototypical applications in these
and other important technologies can be viewed as statistical inverse problems
with complex, massive, high-dimensional and possibly biased/incomplete data.
This unifying theme of inverse problems is particularly appropriate for a
conference and volume dedicated to the memory of Yehuda. Indeed he made
influential contributions to these fields, especially in medical tomography,
biased data, statistical inverse problems, and network tomography.
