Top: volume number density of stars in the modelled cylinder. The blue line represents the data, and violet and red curves are the model predictions before and after the vertical error effect is taken into account. Middle: cumulative number of stars in the cylinder as a function of observed height . The values are normalised to the total number of stars in the TGAS×RAVE thin-disc sample. Bottom: ratio of the observed to predicted number of stars in the vertical bins.