OP,
For Kellogg employment stats, go to Programs -> Full Time MBA -> click “Career Path”. Scroll down a little and the full report will be on your right.
For Ross employment stats, scroll down to the bottom for links under “Employment Data”. The numbers placed to specific firms are in the “Recruiters Guide” link while the “MBA employment data” gives high level stats.
There’s no detailed employment stats for econ majors at Northwestern. The only detailed employment stats for undergrads is the one on MMSS’s website. My guess is econ major alone may not place as well as Ross; but econ + Kellogg certificate, as I detailed above, should put you in better position overall. Obviously, there are some employers that are “used” to Ross; but overall, I believe the uniqueness and advanced treatment of the certificate programs would differentiate you more from others. It seems to me Northwestern place more / better into consulting than high finance (investment banking). The advanced technical skills from the Kellogg cert will be more more applicable to consulting or trading; investment banking entails a lot of busy administrative work at the associate level. Many people have this romantic idea about financial modeling; there’s really not a lot of room to exercise that at the staff level and even if you get involved, valuation isn’t rocket science and is often more of an art. Overall, having a great personality, drive, ability to suck up long hours (and maybe mean superiors within the narcissistic culture), and ability to BS are probably the most important skills. That’s why the industry like hiring grads from top schools even without any finance background.
While placement is a valid consideration, you should also evaluate based on your academic and what you see yourself possibly doing in the future. Do you want a traditional BBA? Or do you want to major in econ or whatever but supplement it with the more focused and highly quantitative courses. Do you think you may become a CPA? The BBA program + 1 extra year would give you courses to fulfill the educational requirement. Do you like math? Do you see yourself involved in data analytics? the Kellogg cert programs would equip you better in that field.