Dawnbreaker

A couple years back, I ended up visiting both programs. I was particularly unhappy with Berkeley IEOR, for the following reasons:
1. Berkeley is vert strong in Stats, EECS, and Math. All the star faculty are in those departments and not IEOR. If you want to do theory, you'll be competing with students in CS theory, which will be a very hard fight. Similarly Statistics and Math departments have great students doing optimization and probability theory. Thus, there is absolutely no reason for someone to choose IEOR over Stats, CS, or Math; and thus all students there seemed to have an inferiority complex.
2. As for the applications, again IEOR doesn't seem to be doing anything very impressive. The west coast scene is mostly driven by the software industry, and focus primarily on CS and Statistics.
Bottom line, the IEOR dept of Berkeley is heavily overshadowed by the other departments there. I am not aware of any students in IEOR who work with outside faculty, and if they do, chances are that they will switch programs. Given these factors, I would advise against Berkeley IEOR, especially given that you have an offer from Columbia which arguably has a stronger IEOR department, and would likely provide better moral support.

A couple years back, I ended up visiting both programs. I was particularly unhappy with Berkeley IEOR, for the following reasons:
1. Berkeley is vert strong in Stats, EECS, and Math. All the star faculty are in those departments and not IEOR. If you want to do theory, you'll be competing with students in CS theory, which will be a very hard fight. Similarly Statistics and Math departments have great students doing optimization and probability theory. Thus, there is absolutely no reason for someone to choose IEOR over Stats, CS, or Math; and thus all students there seemed to have an inferiority complex.
2. As for the applications, again IEOR doesn't seem to be doing anything very impressive. The west coast scene is mostly driven by the software industry, and focus primarily on CS and Statistics.
Bottom line, the IEOR dept of Berkeley is heavily overshadowed by the other departments there. I am not aware of any students in IEOR who work with outside faculty, and if they do, chances are that they will switch programs. Given these factors, I would advise against Berkeley IEOR, especially given that you have an offer from Columbia which arguably has a stronger IEOR department, and would likely provide better moral support.

It depends on what you want to do. If I had no predisposition as to what I wanted to do a PhD in, I personally would choose Berkeley over Cal Tech any day of the week. However, if there's a certain advisor at Cal Tech that's a leader in the field you want to study, go to Cal Tech. For example, one of my interests is Compressed Sensing, and both Candes and Tropp (two big names in the field) are at Cal Tech in the ACM department. It all depends on what you want to do.

If you don't know what you want to do, pick Berkeley. There's just a heck of a lot more breadth there, pure and simple.

@bandinterwebs Also look at people from Haas, some people there also seem to do relevant work.. Anyway, to answer the opening question, I personally think the ranking difference in this case is quite significant. I'd highly recommend Berkeley. Best wishes for your decisions and grad school experience  

Hi @bandinterwebs.. In these cases, I think it would help a lot if you can identify the universities by name, instead of hiding them. That way, you'll get much better and directed responses.
For example, my suggestions will be very different depending on what A is. If A is one of Berkeley or Stanford, I'd highly recommend that you go there. Though the programs are certainly theoretical in nature, the location, possibilities of summer internships, and overall culture will provide the necessary applied "flavor" you might need. On the other hand, I personally think that GATech and Northwestern are not as good as rankings suggest - they end up doing very theoretical work based on last century knowledge. I'd definitely pick a lower ranked program like UIUC or Cornell over them.
PS: Note that I have a bias in my research interests towards statistical decision theory, stochastic control, and convex optimization. All of these are at the interface of IEOR, EECS, and Statistics.

It might be helpful to mention your background, and what you already know. Much of OR is centered around the following, so it might help to brush up on these topics. More directed feedback is possible if you provide further info.
Optimization - start with LP, duality etc. Also study convex optimization, numerical optimization (BFGS, conjugate gradient etc.). If time permits, get some exposure to integer programming using gomory cuts and other methods. Probability theory - basics of probability and statistics starting from common distributions and moment calculations. Bayes rule and its applications are also important. You should also study stochastic processess like markov process, martingales, and Gaussian process models (Bayesian framework) if time permits. Data structures and algorithms - do not under estimate the utility of algorithm design, complexity analysis, and programming in general. Some advanced topics like NP-completeness, approximation, and randomized algorithms are helpful too.

I accepted the offer from Caltech. However, due to some personal commitments that required me to stay in my home country (International student), I had to defer my offer to Fall 2016. I have been working as a research assistant in my undergrad university though, and also doing courses in consultation with Caltech professors. I think it has worked out great though - I can take courses and learn the material without any exam/grade pressure and do the research I like, with sufficient amount of free time.
My research interest is at the interface of optimal control, machine learning, and economics. Applications are in energy markets, online auctions, clinical trials etc.

Hi. If anyone has questions on Systems Engineering, in ChemE, EE, or ME, I can help with my 2 cents. Best wishes to all applicants.
@Argon If you are comfortable with discussing, what happened at MIT? Faculty left, interested group is full, funding issues? Any idea where you are headed (UCB or Madison is a good option I'd guess).