We propose that the majority of quasars at redshift z \sim 1 - 5 formed in the environment of new born collapsed halos with 1-D velocity dispersion \sigma _ { v } ^ { 1 d } \sim 400 { { km s ^ { -1 } } } .
The harboring coefficient f of quasars per halo and the lifetime of quasars depend only on local process , not modulated by the density inhomogeneities on scales larger than the size of the halos .
Thus , the bias of quasars on scale larger than the size of these halos is mainly determined by the parameter \sigma _ { v } used for quasar environment identification .
With this model , the popular structure formation models , like SCDM and LCDM , can be fairly well reconciled with the data of quasars , including a. observed feature of the environment for quasars ; b. redshift evolution of quasar abundance ; c. the two-point correlation functions of quasars .
This bias model predicts that the correlation function of quasars doesn ’ t significantly evolve , or only slightly increases with redshift .