  The increasing use of multivariate methods, and in particular the Matrix
Element Method (MEM), represents a revolution in experimental particle physics.
With continued exponential growth in computing capabilities, the use of
sophisticated multivariate methods-- already common-- will soon become
ubiquitous and ultimately almost compulsory. While the existence of
sophisticated algorithms for disentangling signal and background might naively
suggest a diminished role for theorists, the use of the MEM, with its inherent
connection to the calculation of differential cross sections will benefit from
collaboration between theorists and experimentalists. In this white paper, we
will briefly describe the MEM and some of its recent uses, note some current
issues and potential resolutions, and speculate about exciting future
opportunities.
