Several tests can be made to get a rough idea of the Malmquist effect in a given set of galaxies. They are : (1) The progressive loss of late types pirals (Scd or later), of low luminosity classes, of objects with small rotation velocity, or small internal dispersion, as we go to larger distances. (2) The variation of the slope of the Tully-Fisher relation, of the Faber-Jackson relation or of the Λ index with distance (differential bias).