By integrating the differential equation system of the single-body meteor theory which describes meteor flight in the atmosphere, we show that the population index r depends on the radiant zenithal distance zR. When zR is large, r diminishes, requiring correction in order to obtain reliable number density profiles. A new method is proposed to correct the population index when zR is not zero. Its application to the problem of the 1992 Quadrantids raised by Rendtel et al. shows that corrected values of r vary from r=2.32 to r=2.44 between solar longitudes 283.00 and 283.23 deg.