Neutrino oscillation scenarios involving large angle ν μ ->ν e oscillations are disfavoured in the parameter range Δm 2 /eV 2 10 - 3 by recent results from the CHOOZ reactor-based ν e disappearance experiment. For this reason we extend our previous work on up-down asymmetries for various oscillation scenarios by computing up-down asymmetries and the R ratio for the entire range of interest of Δm 2 . Matter effects in the Earth play a crucial role. We perform a χ 2 fit to the data. We find that, because of the matter effect, the three-flavour maximal mixing model provides a reasonable fit to SuperKamiokande and CHOOZ data provided that the relevant Δm 2 is in the range 4x10 - 4 Δm 2 /eV 2 1.5x10 - 3 .