Left plot: cor(M_r, σ_v | r)∕cor(M_r, σ_v) from volume limited samples with 300 Mpc depth (dotted), 600 Mpc depth (solid line), and 900 Mpc depth (dashed) are shown. Right plot: The results from the samples with various estimates of the absolute magnitude: K-corrected and extinction corrected (dereddened) model magnitudes (solid line), without extinction correction (dotted), without K-correction (dashed), without both, extinction correction and K-correction (dash-dotted).