  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 WIMP mass as well as
the spin-independent WIMP coupling on nucleons will be discussed.
