The coefficients in the P-L-C relation for RR Lyr stars show dependence on the metallicity parameter ΔS. For the range of metallicity and effective temeperatures of RR Lyr stars, the effect of metallicity on the absolute magnitude ranges from 0ᵐ.22 to 0ᵐ.42. Modified P-L-C relations for RR Lyr stars have been derived.
