The redshift completeness as a function of NC. NC is defined for each target as the number of other Main Survey targets within 40 arcsec (numbers with each NC value are annotated in the figure). The various lines show the progress in resolving clustered objects at the outset and after each year of observations for the r-limited Main Survey. Note the bias towards NC > 0 after year 1 and year 2 is the result of increasing the priority of clustered targets (Robotham et al. 2010) in order to avoid being biased against NC > 0 after year 3. The final survey has fully resolved almost all close complexes, leaving only a minimal bias when determining merger rates via close pairs: the redshift completeness is >95 per cent for NC ≤ 5.