Since several of my friends are economics students, I wanted to dispense what wisdom I have about the application process in one sitting, for ease of reference.
My opinion (rather than the wisdom of internet message boards) is this: there are two reasons why you might do a masters degree in economics: to get a fancy job in London (or Johannesburg, or New York, whatever) and earn enough money to bathe in; or, so that you can get into a fancy PhD program in the U.S. and become the next Joseph Stiglitz or Gary Becker.
For private-sector job purposes, you would do well to go to LSE or Oxford (not too hard to get into from UCT). Business science economics will do fine for that, assuming you maintain a 70+ average. It's not necessary to do all that much math or statistics if this is your goal.
For PhD admission, you need a little more. There are two kinds of courses that count in your favour: math (calculus up to linear algebra is the minimum requirement, and real analysis very good to have), and postgraduate econ. Everything else on your transcript will be ignored. Remember, the admissions committee won't know which classes are which, and which ones are the hard ones, so you can mention that in your SoP, as long as it doesn't become a facsimile of your grades. Here, I'm focusing on American, or good Canadian or British PhDs (e.g. UBC, U Western Ontario, Queen's University, U Toronto, LSE, Oxford, or UCL), since the process is similar for most of them. (And because most economists worth reading have done their PhDs in such places.)
Although UCT has sent people from business science straight to PhD, you could do up to MAM300W to give yourself a bit of an edge. (The material becomes very useful in micro theory and econometrics later on.)
Roughly, you need the following to put together a PhD application:
- GRE scores. Only take the general test. This costs around $160, and you can book an appointment online at www.gre.org. There are three sections: analytical writing (two essays - one argumentative and one where you analyse a given argument), verbal (vocabulary, grammar, comprehension) and quantitative (high-school level algebra, geometry, numeracy). For economics, the only thing that counts is your score on the quantitative section, which is (bizzarely) scored on a scale from 200-800. If you want to get into a top-50 US programme, you need to crack 770 on this section, and 800 for any school ranked above 25.
- Three letters of recommendation. This is, by far, the most important part of your application.
- A personal statement of purpose. This should answer the questions "Why do I want a PhD?" "Why should School X choose me?" "What makes me qualified to study this?" etc.
- (optional) A diversity statement.
- (optional) A writing sample.
- The admissions committee gets the 800 - 1600 (in the case of MIT) applications sometime in January. They check to see if you have a GRE Q score of >780. If not, your application goes in the recycling bin.
- Assuming you get through, they check your letters of reccomendation to see if they know and trust your letter writers, and to see if your letter-writers haven't said anything bad about you.
- Remember, everyone's letter says that student X is hardworking and smart. That's essentially noise.
- The way you can deal with this is to get your reccomender to write about specific research projects that you have done for her ("Under my direction, Jesse collected data from a field experiement in which subjects played three rounds of the dictator game. Jesse helped clean the data and performed some initial econometric analysis for me...")
- If you get through (and by then, it's down to about 200 people) they read through your transcripts, see if you've taken real analysis and maybe even topology or measure theory, etc. Here is where your grades and math background can help you.
- After that, they might read your personal statement, reread your letters, etc, trying to determine if you are a good fit for their program. For example, if you tell UChicago that you're a heterodox economist who wants to break the back of neoliberal capitalism, wave your $90 application fee goodbye.
- The best place to look for advice is the TestMagic Forum. This is a discussion board dedicated to economics PhD or masters applicants, and many past applicants (current students) continue to post there. Most of the questions you have will already have been answered, so search the forum or check the permanently posted topics (near the top of the page).
- A good (but slightly outdated) page is econphd.net. If you want to see what the material in (the first year of) econ grad school is like, check out the extensive collection of lecture notes. If you want a step-by-step guide through the admissions process, read the admissions guide. If you want to see where you should shoot for in your favourite subfield (beyond the obvious - yes, we all know Harvard and Berkeley are amazing at everything, but you can discover some interesting anomalies here: Caltech is rubbish at macro, Northwestern kills most of the Ivy league at IO and Oxford is not as good as you might think...), browse the rankings. (Slightly newer rankings can be found here [scroll down], though access is limited to the top 10).