The most common methods to derive the distance to globular clusters using RR Lyrae variables are reviewed , with a special attention to those that have experienced significant improvement in the past few years .
From the weighted average of these most recent determinations the absolute magnitude of the RR Lyrae stars at [ Fe / H ] = -1.5 is M _ { V } = 0.59 \pm 0.03 , corresponding to a distance modulus for the LMC ( m - M ) _ { 0 } = 18.48 \pm 0.05 .