  We reexamine the model-independent data analysis methods for extracting
properties of Weakly Interacting Massive Particles (WIMPs) by using data
(measured recoil energies) from direct Dark Matter detection experiments
directly and, as a more realistic study, consider a small fraction of residue
background events, which pass all discrimination criteria and then mix with
other real WIMP-induced signals in the analyzed data sets. In this talk, the
effects of residue backgrounds on the determination of the mass of halo Dark
Matter particle as well as on the reconstruction of its one-dimensional
velocity distribution function will be discussed.
