Difference in the distance measurements for our clusters by comparing the fundamental plane distances with the redshift distances depending on the number of early-type galaxies N_ETG per group. Black dashed line: average ratio per early-type galaxies multiplicity bin. Red solid line: 1-σ intervals. Green dashed line: expected progression of the 1-σ intervals around one based on the root mean square of our fundamental plane distance error of 0.0920. Magenta dotted line: reference for where both distance measurements yield exactly the same values.