3.3 Sampling Correction
The groups used in the calibration are all small nearby groups with the following mean luminosity function:
| MG < | -19 | -18 | -17 | -16 |
 (MG)
| 1.3 | 3.2 | 4.5 | 6.4. |
In larger groups, a size of sample correction is required since the larger the sample (population of group) the greater the probability of occurance of outstanding objects. The correction was determined through a comparison of the distance moduli derived for the Virgo cluster taken as a whole or divided into smaller groups and subgroups. If N18 is the number of galaxies having MG < - 18 in a group, the correction to the modulus derived as explained in Sections 3.1 and 3.2 above is
µ = 2.0 (log
N18 - 0.5).