on the sky have a number of unavoidable systematic problems. First, in spite of their large projected surface density, the group candidates may include interlopers with redshifts substantially different from the systemic mean. Among the 100 systems originally identified by Hickson, 92% have $N \geq 3$; only 69% actually have $N \geq 4$ (Hickson et al.  1992). Selection on the sky unavoidably introduces correlations of group properties with distance. For example, nearby systems with a large angular scale are underrepresented in these catalogs.

The CfA2 + SSRS2 Redshift Survey
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We select compact groups from redshift surveys which include 14,383 galaxies. CfAnorth covers the declination range $8.5^\circ \leq \delta \leq 44.5^\circ$ and right ascension range $8^{h} \leq \alpha \leq 17^{h}$ (B1950) and includes 6500 galaxies (Geller & Huchra 1989; Huchra et al.  1990; Huchra et al.  1995). CfAsouth covers the region $-2.5^\circ \leq \delta \leq 48^\circ$ and $20^{h} \leq \alpha \leq 4^{h}$ and includes 4283 galaxies (Giovanelli & Haynes 1985; Giovanelli et al.  1986; Haynes et al.  1988; Giovanelli & Haynes 1989; Wegner, Haynes & Giovanelli 1993; Giovanelli & Haynes 1993; Vogeley 1993). SSRS2 includes 3600 galaxies and is complete over 1.13 steradians of the of the southern galactic cap 