Distribution of distances above the Galactic plane of DA white dwarfs in the sample of Krzesinski et al. (2009) and in our simulated sample as a function of the magnitude. The small symbols correspond to the results of our Monte Carlo simulations, while the large ones represent the observational data. Empty symbols correspond to white dwarfs with derived masses smaller than 0.49 M_⊙, whereas filled symbols represent white dwarfs with measured masses larger than this value. The top panel presents the original data of Krzesinski et al. (2009), while the bottom panel shows revised distances obtained assuming that the mass of each of these white dwarfs is 0.49 M_⊙.