It depends on which college you apply to. If you are applying to study statistics through the math major at Cornell with a stat concentration, your intended major won't impact your application. If you are applying to do the biometry and statistics major through CALS, that choice would impact your chances. Given biometry/statistics is a relatively small major, I'm not sure there are readily available stats for the competitiveness of that major. You may want to also look into something like Operations Research in Engineering. I'm not that familiar with the major, but my impression is that it's a lot of advanced applied statistics (plus other analytical methods).