Testing the IMF. Cepheid counts for the complete region up to V = 12. Up to V = 9 the observational Cepheid catalogues are considered as being complete for the whole sky while for the interval 9 < V ≤ 12 they are supposed to be complete for δ ≤ 29. In the interval 9 < V ≤ 12, an additional cut (|b| ≤ 10) is applied to avoid contamination of the observational sample. The green line indicates the observational counts, the grey region is the region within 1σ. Filled red dots are for the simulations with the Marshall et al. (2006) extinction model, while blue triangles are simulations with the Drimmel & Spergel (2001) extinction model. Error bars are due to Poisson noise. We note how the DM, that is Kroupa-Haywood IMF, is the variant that better fits the observational data, while HRV, that is Haywood-Robin IMF and SV (Salpeter IMF), are more than 5σ away from the observational data.