@pop04], the ROSAT-ESO Flux-Limited X-Ray (REFLEX) Galaxy Cluster Survey [@sch02]. A variant, simplified method, which is called pseudo-KL eigenmodes method is applied to the IRAS Point Source Catalog Redshift Survey (PSC$z$) [@teg00], the 2dF Galaxy Redshift Survey [@teg02], and SDSS [@teg03].

In applying the KL technique to cosmology, it is important to have a good method to theoretically compute the power spectrum of the KL modes. This is not a trivial task, since the observed distribution of the galaxies are distorted by observational effects including peculiar velocity distortions, light-cone effects, varying selection functions, and complex shape of the survey geometry. Among these, the light-cone effect has never been taken into account in previous applications of the KL method to redshift surveys. The light-cone effects consist of evolutionary effects and geometric effects. The clustering of galaxies evolves with redshift through evolution in mass clustering, and evolution in the biasing of galaxies. The comoving distance is not proportional to the redshift and the apparent clustering pattern in redshift space is not the same as in comoving space. For shallow redshift surveys in which the redshift range is, e.g., $0 {\lower.5ex\hbox{{$\; \buildrel < \over \sim \;$}}}z
{\lower.5ex\hbox{{$\; \buildrel < \over \sim \;$}}}0.2$, the 