Star forming regions are plagued with reddedning and uncertainties in proper motion and distance that become significant already at the distance of Orion (~ 400 pc) even in the GaiaDR2 era. In this short presentation I would like to present a study of an assessment of completeness of sample using E(B-V) maps such as the PAN-STARRS cube. Using the randomness of Fourier modes and age uncertainties for the embedded stars, I find that ≈ 20% of stars may yet be missing.