GhostKnockoff.GetCorStudy
                        Calculate study correlation
GhostKnockoff.filter    GhostKnockoff filter
GhostKnockoff.fit       Feature importance score generator
GhostKnockoff.prelim    Preliminary data management for GhostKnockoff
GhostKnockoff.prelim.Meta
                        Additional preliminary data management for
                        GhostKnockoff if multiple studies are involved
